Comprehensive Guide to Flood Zones in All 50 States - And What You Can Do About It (2025)
About This Guide:
Flooding is the most common and costly natural disaster in the United States, affecting every region of the country. Whether caused by heavy rains, hurricanes, rapid snowmelt, or coastal storm surges, floods pose significant threats to homes, properties, and lives. Understanding the flood risk in your area is critical for homeowners, insurers, property managers, and developers.
While flooding itself doesn’t directly cause sewer backups in well-maintained, closed sanitary systems, heavy rainfall and flood conditions often lead to system overloads due to infiltration, surface runoff, and groundwater intrusion. This is especially true in areas with aging infrastructure, combined sewer systems, or improperly sealed connections. As a result, flood conditions frequently contribute to or trigger sewer backups—even in homes not directly inundated by rising waters.
This guide offers a comprehensive, state-by-state breakdown of federally recognized flood zones based on FEMA’s Flood Insurance Rate Maps (FIRMs) and other authoritative data. It is designed to support SewerAlarm’s mission of helping Americans proactively detect and mitigate sewer backup risks associated with stormwater intrusion, system overloads, and flooding-related pressure events.
This guide is especially valuable for:
• Homeowners and landlords evaluating flood and sewer risk
• Licensed plumbers advising clients on flood-prone installations
• Insurance companies and adjusters assessing risk exposure
• Real estate professionals educating buyers and sellers
Flood Zone Classifications:
Flood zones are determined by the Federal Emergency Management Agency (FEMA) and are grouped into several categories:
High-Risk Areas (Special Flood Hazard Areas - SFHAs):
• Zone A: Areas subject to inundation by the 1% annual chance flood event.
• Zone AE: Areas where base flood elevations (BFEs) have been determined.
• Zone AH: Areas of shallow flooding with BFEs.
• Zone AO: Areas with shallow flooding where depths are between 1 and 3 feet.
• Zone AR: Areas with increased flood risk due to the restoration of a flood protection system.
• Zone V and VE: Coastal areas with additional velocity hazard due to wave action.
Moderate- to Low-Risk Areas:
• Zone X (shaded): Areas of moderate flood hazard, usually between the limits of the 100-year and 500-year floods.
• Zone X (unshaded): Areas of minimal flood hazard.
Undetermined Risk Areas:
• Zone D: Areas with possible but undetermined flood hazards.
Each state section includes:
• General flood risk overview
• Notable rivers, coasts, and topographies contributing to flood risk
• Zones A, AE, AO, AH, V, VE, and AR prevalence
• Counties with high SFHA presence
• FEMA flood map access links
• Historical flood events with sewer relevance
• SewerAlarm installation priority areas
Overview: Alabama’s flood risks stem from hurricanes and tropical storms along the Gulf Coast, as well as flash and riverine flooding inland. The Tennessee, Black Warrior, and Alabama Rivers contribute to frequent high-water events across the state.
Primary Flood Zones: AE and A zones stretch across most rivers and creeks. AO zones are concentrated in older neighborhoods of Birmingham, Montgomery, and Mobile.
Localized Hotspots:
Mobile (Mobile County): VE and AE zones along Mobile Bay and Three Mile Creek. Coastal and river flooding combine with outdated drainage systems.
Birmingham (Jefferson County): AO zones in North Birmingham, Ensley, and Valley Creek corridor.
Montgomery (Montgomery County): AE zones near the Alabama River; basement backups common in flat mid-century subdivisions.
High-Risk Counties: Mobile, Jefferson, Montgomery, Tuscaloosa, Baldwin. FEMA maps place nearly 150,000 properties in high-risk flood zones.
Historic Flood Events:
2014 Flash Floods in Birmingham: Over 6 inches of rain in a few hours overwhelmed drainage systems.
Hurricane Sally (2020): Devastated coastal communities with over 30 inches of rain.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly recommended for homes in floodplains across Birmingham and Mobile, especially those built before 1980 with minimal floodproofing or sewer backflow valves.
Overview: Alaska’s flood risk includes snowmelt flooding, ice jams, glacial lake outbursts, and coastal storm surge. Due to its remote communities and permafrost, sewer infrastructure is minimal or fragile.
Primary Flood Zones: AE zones along major rivers like the Yukon, Kuskokwim, and Copper. AO zones in Fairbanks and Bethel.
Localized Hotspots:
Fairbanks (Fairbanks North Star Borough): AO zones along Chena River.
Bethel and Nome: AE zones along river mouths and coastal floodplains.
Juneau: AE zones near glacial flood pathways.
High-Risk Boroughs: Fairbanks North Star, Yukon-Koyukuk, Bethel, Juneau.
Historic Flood Events:
2009 Eagle Flood (Ice Jam): Destroyed over half the village.
2014 Glacial Flood near Juneau: Repeated outburst floods from Mendenhall Glacier.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Useful in Fairbanks and Juneau homes with indoor plumbing near known ice jam or glacial melt zones.
Overview: Arizona experiences some of the most intense flash flooding in the country due to monsoon thunderstorms and rugged desert terrain. While rainfall totals are typically low, the arid landscape cannot absorb water quickly, leading to rapid runoff and dangerous conditions.
Primary Flood Zones: AO zones dominate Phoenix and Tucson metropolitan areas. AE and A zones are found along the Salt, Gila, and Santa Cruz Rivers.
Localized Hotspots:
Phoenix (Maricopa County): AO zones in Arcadia, South Mountain, and Laveen neighborhoods. AE zones along the Salt River and its flood channels.
Tucson (Pima County): AE and AO zones near the Santa Cruz River, Pantano Wash, and Rillito Creek.
Flagstaff and Prescott: Flash floods along steep canyons and post-wildfire areas.
High-Risk Counties: Maricopa, Pima, Coconino, Yavapai.
Historic Flood Events:
2014 Phoenix Flood: 3 inches of rain fell in 1 hour. Freeways and basements flooded across the metro.
2021 Monsoon Season: Major floods hit Gila Bend and central Arizona.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential in Phoenix neighborhoods with slab-on-grade or basement foundations, especially near washes and flood control canals. Install in Tucson homes built prior to 1990 with minimal grading.
Overview: Arkansas is heavily impacted by riverine and flash flooding, particularly in the Arkansas and Mississippi River valleys and the Ozark foothills. Heavy seasonal rains and slow-draining clay soils contribute to frequent basement and sewer-related flooding.
Primary Flood Zones: AE and A zones follow the Arkansas, White, and Ouachita Rivers. AO zones appear in low-gradient suburbs of Little Rock and Pine Bluff.
Localized Hotspots:
Little Rock (Pulaski County): AE and AO zones along Fourche Creek and Rock Creek. Older neighborhoods in Midtown and College Station flood often.
Fort Smith and Jonesboro: AE zones along the Arkansas River and Craighead Forest Park tributaries.
High-Risk Counties: Pulaski, Jefferson, Sebastian, Craighead. FEMA maps designate thousands of structures within SFHAs across these areas.
Historic Flood Events:
2019 Arkansas River Flooding: Record flooding impacted Fort Smith and Little Rock. Long-duration flooding damaged hundreds of structures.
2008 Spring Floods: Inundated parts of eastern Arkansas and the Mississippi Delta region.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Prioritize installation in Little Rock neighborhoods built pre-1980 and in floodplains along Fourche Creek. Also recommended in rural counties with well water and septic systems vulnerable to rising groundwater.
Overview: California experiences flooding from coastal storms, riverine overflow, and post-wildfire debris flows. Low-lying areas in the Central Valley, urban basins like Los Angeles, and levee-protected communities in Sacramento are all high risk.
Primary Flood Zones: AE and A zones along the Sacramento, San Joaquin, and Los Angeles Rivers. AO zones in older LA neighborhoods and Bay Area suburbs.
Localized Hotspots:
Sacramento (Sacramento County): AE zones along the American and Sacramento Rivers. High levee failure risk.
Los Angeles (LA County): AO zones in South LA, Watts, and San Fernando Valley. AE zones along the LA River.
San Jose and Oakland: AE zones along Guadalupe River and Estuary waterfronts.
High-Risk Counties: Sacramento, Los Angeles, Alameda, San Joaquin, Riverside.
Historic Flood Events:
1997 Central Valley Flood: $2 billion in damages.
2023 Atmospheric River Events: Repeated floods in Monterey, Santa Cruz, and low-lying LA neighborhoods.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential in levee-dependent Central Valley communities, East Bay homes built before 1980, and urbanized LA neighborhoods with minimal runoff capacity.
Overview: Colorado faces diverse flood threats—flash floods in mountainous terrain, riverine flooding along the South Platte and Arkansas Rivers, and urban flooding in Denver and Boulder. Wildfires also contribute to debris flow and flood risk.
Primary Flood Zones: AE and A zones are found along all major rivers and streams. AO zones exist in flood-prone subdivisions in Denver and Fort Collins.
Localized Hotspots:
Denver (Denver County): AO and AE zones in Globeville, Elyria-Swansea, and Westwood neighborhoods.
Boulder (Boulder County): AE zones along Boulder Creek and Fourmile Canyon.
Colorado Springs: AE zones along Fountain Creek and Shooks Run.
High-Risk Counties: Denver, El Paso, Boulder, Larimer, Jefferson.
Historic Flood Events:
2013 Front Range Floods: Caused by days of rain. Over 19,000 homes damaged.
1976 Big Thompson Canyon Flood: Flash flood killed 144 people.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Especially critical in older Denver neighborhoods, canyon towns, and post-wildfire zones.
Overview: Connecticut’s flood risks stem from its proximity to the Atlantic Ocean, major rivers like the Connecticut and Housatonic, and seasonal storms. Many towns have areas mapped in high-risk flood zones, especially along the coast and low-lying inland areas.
Primary Flood Zones: Zones AE and VE dominate the coastline. Inland areas near rivers often fall into Zones A or AE. Flash flood-prone urban areas can include Zone AO.
High-Risk Counties: Fairfield, New Haven, and New London counties have the highest concentrations of SFHAs.
Historic Flood Events: The 1955 flood caused by hurricanes Connie and Diane devastated much of the state, changing how Connecticut manages floodplain development.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Particularly recommended in homes with basements or ground-level plumbing in low-lying parts of Bridgeport, Norwalk, Stamford, and New London.
Overview: Delaware's low elevation, dense river network, and Atlantic coast exposure make it one of the most vulnerable states to flooding per square mile. The Delaware Bay, Christina River, and tributaries of the Nanticoke and Indian Rivers create both tidal and inland risks. Much of the state is less than 10 feet above sea level.
Primary Flood Zones: VE and AE zones are present in coastal Sussex County. AE and AO zones dominate the Christina River watershed and flat inland areas near Seaford, Milford, and Dover.
Localized Hotspots:
Wilmington (New Castle County): AE zones flank the Brandywine and Christina Rivers. AO zones in Southbridge and Browntown—neighborhoods prone to sewer backups.
Dover (Kent County): AE and AO zones affect neighborhoods along the St. Jones River.
Rehoboth Beach and Dewey Beach (Sussex County): VE zones dominate oceanfront zones; AE zones inland where dune overflows collect.
High-Risk Counties: New Castle, Kent, and Sussex. Over 17% of Sussex County’s land area lies within a mapped floodplain.
Historic Flood Events:
Hurricane Sandy (2012): Coastal flooding reached far inland. Sewer systems in Lewes and Bethany Beach overflowed.
1999 Hurricane Floyd: Flooded inland towns across New Castle County.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Prioritize Wilmington homes with combined sewer systems, as well as coastal homes with basements or crawlspaces in Lewes, Milton, and Bethany Beach. Also critical in Dover neighborhoods near the St. Jones River.
Overview: Florida is the most flood-prone state in the country. With over 1,300 miles of coastline, low elevation, and tropical storm exposure, nearly every property is at risk. Additionally, Florida’s high water table increases the threat of sewer backups during flooding events.
Primary Flood Zones: VE and AE zones dominate the coastline, barrier islands, and bayfront areas. AO and AH zones are scattered throughout inland flatlands and older developments. Zone A covers the Everglades and inland riverine floodplains.
Localized Hotspots:
Miami-Dade County: AO and AE zones in Little Havana, Hialeah, and Homestead. Low-lying neighborhoods with aging infrastructure.
Tampa Bay Region: VE and AE zones in St. Petersburg, Clearwater, and Hillsborough Bayfront communities.
Jacksonville and Orlando: AE zones along the St. Johns River and AO zones in flat inland suburbs.
High-Risk Counties: Miami-Dade, Broward, Hillsborough, Pinellas, Duval. Nearly 2 million properties in Florida are within SFHAs, the most of any state.
Historic Flood Events:
Hurricane Ian (2022): Caused record-breaking storm surge and inland flooding in southwest Florida.
Hurricane Irma (2017): Over 6.5 million evacuated. Extensive sewer overflows across southeast Florida.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Mandatory in any Florida property with basement or slab-level drains, especially in older homes across Tampa, Miami, and Fort Lauderdale. Critical for residents of low-lying manufactured home parks and inland subdivisions.
Overview: Georgia experiences a variety of flood threats including flash flooding in the north Georgia mountains, riverine flooding in the Piedmont and Coastal Plain, and storm surge in the southeast coastal areas. Its humid subtropical climate and frequent severe weather events increase the likelihood of flooding statewide.
Primary Flood Zones: AE and A zones are common along the Chattahoochee, Oconee, and Altamaha rivers. VE zones are present along the coastal barrier islands. AO zones appear in older neighborhoods of Atlanta, Savannah, and Macon.
Localized Hotspots:
Atlanta (Fulton County): AO and AE zones in Peoplestown, Vine City, and along Proctor Creek. Combined stormwater issues and topographical bowls cause recurring basement flooding.
Savannah (Chatham County): AE and VE zones near the Savannah River and marshland areas. Tidal surge and king tides pose risk even during minor storms.
Augusta and Macon: AE zones along the Savannah and Ocmulgee Rivers respectively.
High-Risk Counties: Fulton, Chatham, Bibb, Richmond, Dougherty. FEMA reports nearly 100,000 properties in Georgia are located within SFHAs.
Historic Flood Events:
2009 Atlanta Floods: Caused by over 20 inches of rain, this disaster led to sewer overflows in metro Atlanta and $500 million in damages.
Hurricane Irma (2017): Caused coastal and inland flooding. Surge impacted Tybee Island and St. Marys.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Prioritize installation in older Atlanta neighborhoods with combined sewer systems, Savannah's historic district homes, and floodplain properties along the Chattahoochee and Flint Rivers.
Overview: Hawaii’s mountainous terrain and tropical rainfall contribute to frequent flash flooding. Coastal inundation, tsunamis, and urban drainage problems in Honolulu and Hilo exacerbate risks.
Primary Flood Zones: AE and VE zones along coastlines and river valleys. AO zones common in Honolulu and Wailuku.
Localized Hotspots:
Honolulu (Oahu): AO and AE zones in Kalihi, Manoa Valley, and Waikiki.
Hilo (Big Island): AE zones along Wailuku River.
Wailuku and Lahaina (Maui): AE and AO zones near streams and gulches.
High-Risk Counties: Honolulu, Hawaii, Maui, Kauai.
Historic Flood Events:
2004 Manoa Flood: Over $85 million in damage to homes and UH campus.
2018 Kauai Rainfall Record: 50 inches in 24 hours caused landslides and major floods.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential for Honolulu homes with slab-level plumbing or floor drains near streambeds. Install in Lahaina and Hilo neighborhoods vulnerable to river or coastal surge.
Overview: Idaho’s mountainous terrain makes it prone to flash flooding, particularly from rapid snowmelt and high-intensity storms. Riverine flooding is also common in major valleys such as those surrounding the Boise, Snake, and Clearwater Rivers.
Primary Flood Zones: AE and A zones dominate along river basins. AO zones are found in parts of Boise and Twin Falls.
Localized Hotspots:
Boise (Ada County): AE zones near the Boise River and AO zones in floodplain neighborhoods like Garden City.
Lewiston (Nez Perce County): AE zones near the confluence of the Snake and Clearwater Rivers.
Twin Falls and Idaho Falls: AE zones along river corridors and AO zones in flat residential subdivisions.
High-Risk Counties: Ada, Nez Perce, Canyon, Bonneville.
Historic Flood Events:
1996 Snowmelt Floods: Widespread flooding in southern Idaho after record snowfall and rain.
2017 Spring Floods: Damaged over 100 roads and hundreds of homes statewide.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Recommended in Boise’s river-adjacent neighborhoods and floodplain homes across southern Idaho where basement plumbing is common.
Overview: Illinois' flood vulnerability is tied to the Mississippi and Illinois Rivers, the Des Plaines River, and highly urbanized Chicagoland. Suburban sprawl and combined sewer systems in Chicago increase risk.
Primary Flood Zones: AE and A zones dominate floodplains along major rivers. AO zones appear in older Chicago neighborhoods and suburbs.
Localized Hotspots:
Chicago (Cook County): AO and AE zones on the South Side, near Bubbly Creek and the Calumet River.
Peoria and Alton: AE zones along the Illinois and Mississippi Rivers.
Rockford and East St. Louis: AO and AE zones in legacy industrial corridors.
High-Risk Counties: Cook, Madison, St. Clair, Peoria. FEMA designates tens of thousands of at-risk properties.
Historic Flood Events:
1996 and 2013 Chicagoland Floods: Massive sewer backups and stormwater surges.
2019 Mississippi River Flooding: Record levels in southwest Illinois.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-urgency in older Chicago neighborhoods and riverfront suburbs with combined sewer infrastructure. Useful across industrial cities with aging stormwater systems.
Overview: Indiana faces recurring riverine flooding from the Wabash, White, and Ohio Rivers, and from flash floods in hilly southern terrain. Many central Indiana communities, including Indianapolis, are vulnerable to basement backups from undersized or aging sewer lines.
Primary Flood Zones: AE and A zones across most rivers and creeks. AO zones appear in flatter neighborhoods in Indianapolis and Fort Wayne.
Localized Hotspots:
Indianapolis (Marion County): AO zones near Fall Creek and White River; outdated CSOs increase sewer backup risk.
Evansville (Vanderburgh County): AE zones around the Ohio River and Pigeon Creek.
Bloomington and Muncie: AE zones follow Salt Creek and White River branches.
High-Risk Counties: Marion, Vanderburgh, Allen, Monroe. Thousands of properties lie within FEMA SFHAs.
Historic Flood Events:
2008 Statewide Floods: Caused $1 billion in damages. Particularly damaging to central and eastern Indiana.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Highly recommended in older Indianapolis neighborhoods (e.g., Broad Ripple, Fountain Square), Evansville lowlands, and college town housing.
Overview: Iowa is at high risk of riverine flooding due to its extensive network of rivers, especially the Mississippi, Missouri, Cedar, and Des Moines. Flash flooding and ice jam flooding are also common. Repeated heavy rains over saturated ground lead to frequent sewer overflows and infrastructure stress in urban areas.
Primary Flood Zones: AE and A zones along major rivers and their tributaries. AO zones are present in older parts of Des Moines, Cedar Rapids, and Davenport.
Localized Hotspots:
Cedar Rapids (Linn County): AE zones around the Cedar River; devastated by 2008 and 2016 floods.
Des Moines (Polk County): AO and AE zones in neighborhoods near the Des Moines and Raccoon Rivers.
Davenport (Scott County): AE zones along the Mississippi Riverfront.
High-Risk Counties: Linn, Polk, Scott, Johnson. FEMA and Iowa Flood Center data highlight thousands of vulnerable homes statewide.
Historic Flood Events:
2008 Iowa Floods: Among the costliest in U.S. history. Over 40,000 people evacuated in Cedar Rapids.
1993 Midwest Floods: Impacted southeast Iowa, especially along the Mississippi.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential in flood-prone Cedar Rapids neighborhoods, Des Moines riverfronts, and Mississippi-adjacent cities. Prioritize homes with basements or flat-grade drainage.
Overview: While often associated with droughts and tornadoes, Kansas experiences frequent flooding, especially in eastern and central regions. Flash floods, backed-up drainage systems, and overbank flooding from the Kansas and Arkansas Rivers affect cities and rural communities alike.
Primary Flood Zones: AE and A zones follow the Kansas, Neosho, and Arkansas Rivers. AO zones are present in lower-lying parts of Wichita and Topeka.
Localized Hotspots:
Wichita (Sedgwick County): AE zones along the Arkansas River and Chisholm Creek. AO zones in central and south Wichita neighborhoods.
Topeka (Shawnee County): AE zones near the Kansas River and AO zones in hilly neighborhoods with poor runoff control.
Emporia and Manhattan: Recurrent flooding along the Cottonwood and Big Blue Rivers.
High-Risk Counties: Sedgwick, Shawnee, Douglas, Riley. Kansas has experienced multiple FEMA-declared flood disasters in the past 20 years.
Historic Flood Events:
1993 Midwest Flood: Widespread damage in eastern Kansas. Arkansas River overflowed significantly.
2007 and 2019 Floods: Flash floods overwhelmed parts of Wichita and Topeka, causing sewer overflows and damage to thousands of homes.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-priority in Wichita, Topeka, and smaller towns near rivers. Critical in neighborhoods with aging sewer infrastructure, especially those without backflow prevention.
Overview: Kentucky’s flood risks arise from its dense network of rivers, especially the Ohio, Kentucky, and Cumberland Rivers. Mountainous terrain in the eastern part of the state contributes to deadly flash flooding, while low-lying cities along riverbanks are vulnerable to prolonged inundation. Aging infrastructure in many rural and urban areas increases the risk of sewer backups.
Primary Flood Zones: AE and A zones span riverbanks and floodplains. AO zones are present in flatter areas of Lexington, Louisville, and eastern Kentucky towns built along hollows and creek beds.
Localized Hotspots:
Louisville (Jefferson County): AO and AE zones along Beargrass Creek and the Ohio River floodwall boundary. Sewer systems in the Portland and Shawnee neighborhoods are known for backflow issues during storms.
Lexington (Fayette County): AE zones along Town Branch and Wolf Run. AO zones appear in mid-century subdivisions with limited drainage grading.
Eastern Kentucky (Breathitt, Perry, Knott Counties): AE zones along Troublesome Creek, North Fork Kentucky River. Flash floods frequent in communities like Hazard and Jackson.
High-Risk Counties: Jefferson, Fayette, Pike, Perry, Breathitt. FEMA data and recent flood disasters show significant vulnerability throughout Appalachia and the Ohio Valley corridor.
Historic Flood Events:
2022 Eastern Kentucky Flood: Catastrophic flash flooding in Breathitt, Knott, and Letcher counties. At least 45 deaths and hundreds of homes destroyed.
1997 Ohio River Flood: Impacted Louisville and many western counties. Long-duration water exposure overwhelmed urban sewer systems.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical for homes in eastern Kentucky hollows and older city neighborhoods in Louisville and Lexington with basement plumbing. Especially important in areas without modern backflow prevention infrastructure.
Overview: Louisiana is one of the most flood-prone states in the nation. Much of its land lies at or below sea level, particularly in and around New Orleans. Flood risk is driven by hurricanes, levee breaches, backwater flooding from the Mississippi River, and heavy rain events. Extensive wetland loss and land subsidence compound the problem.
Primary Flood Zones: VE zones dominate coastal parishes. AE and A zones extend inland along rivers and low-lying bayous. AO and AH zones are common in the older urban drainage basins of New Orleans.
Localized Hotspots:
New Orleans (Orleans Parish): AO and AE zones in Lakeview, Gentilly, the Lower 9th Ward, and Mid-City. These areas are below sea level and protected by levees and pumps.
Baton Rouge (East Baton Rouge Parish): AE zones along the Mississippi River, and flash flood-prone areas in Garden District and Brookstown.
Lafayette and Houma: AE and VE zones impacted by inland surge and poor drainage during storm events.
High-Risk Parishes: Orleans, Jefferson, St. Bernard, Terrebonne, Plaquemines, Lafourche. FEMA maps designate a large portion of these parishes in SFHAs.
Historic Flood Events:
Hurricane Katrina (2005): Devastated New Orleans. 80% of the city flooded due to levee failures. Over 1,800 fatalities.
2016 Baton Rouge Floods: Over 20 inches of rain in three days. 146,000 homes damaged.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical for New Orleans homes with basement utilities or slab-on-grade bathrooms, especially in neighborhoods relying on pump stations. Strongly advised in Baton Rouge, Houma, and Thibodaux floodplains.
Overview: Maine is prone to flooding due to snowmelt, coastal storms, and river overflows. The state’s rugged coastline and numerous rivers contribute to periodic flood risks, especially in spring and during hurricane season.
Primary Flood Zones: Coastal towns along the Gulf of Maine often fall in Zones AE and VE. Inland areas experience Zone A and AE designations around major rivers.
High-Risk Counties: Cumberland, York, and Penobscot counties have the most significant concentrations of SFHAs.
Historic Flood Events: In 1987, a major spring flood caused extensive damage across central and western Maine due to snowmelt and heavy rain.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical for properties in floodplains along the Penobscot, Kennebec, and Androscoggin rivers, and in coastal towns such as Portland, Saco, and Bar Harbor.
Overview: Maryland’s diverse terrain includes the Atlantic coast, Chesapeake Bay tributaries, and inland mountain streams—each posing different flood threats. Flash floods are common in western Maryland’s hilly terrain, while tidal and storm surge flooding threatens Baltimore and Eastern Shore communities.
Primary Flood Zones: VE and AE zones along the Chesapeake Bay and oceanfront areas. AO zones occur in older Baltimore neighborhoods and Prince George’s County subdivisions.
Localized Hotspots:
Baltimore City: AO and AE zones in areas like Dundalk, Inner Harbor, and Edmondson Village. Combined sewer systems and high impervious surfaces drive backups.
Ellicott City (Howard County): AE and AO zones. Known for catastrophic flash floods in 2016 and 2018 that overwhelmed historic Main Street.
Annapolis and Eastern Shore: AE and VE zones along Spa Creek, Kent Island, and Cambridge.
High-Risk Counties: Baltimore City, Howard, Anne Arundel, Prince George’s, Talbot. FEMA estimates 60,000+ properties across Maryland are in SFHAs.
Historic Flood Events:
2016 & 2018 Ellicott City Flash Floods: Caused multiple fatalities, infrastructure loss, and renewed focus on urban drainage.
Hurricane Isabel (2003): Storm surge flooded Annapolis and Baltimore’s Fells Point area.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-urgency areas include flood-prone neighborhoods in Baltimore City, Ellicott City’s Main Street corridor, and Annapolis homes near tidal creeks. Install in older homes with basement plumbing throughout the Baltimore-Washington corridor.
Overview: With 1,500+ miles of coastline and major rivers like the Charles, Mystic, and Merrimack, Massachusetts faces risk from tidal surge, fluvial flooding, and urban runoff. Boston and surrounding communities are particularly vulnerable due to aging infrastructure and low-lying topography.
Primary Flood Zones: Zones VE (coastal cities: Revere, Quincy, Hull); AE zones flank the Merrimack and Charles Rivers; AO zones found in low-gradient cities with dated sewer systems.
Localized Hotspots:
Boston (Suffolk County): AO and AE zones in Dorchester, East Boston, South End, and near Fort Point Channel. CSO infrastructure poses sewer backup risk.
Quincy and Revere (Norfolk and Suffolk Counties): VE zones common along the waterfront. AO zones in post-war subdivisions with outdated plumbing.
Lawrence and Lowell (Middlesex and Essex Counties): AE zones along the Merrimack River with a history of ice jam and rain-on-snow floods.
High-Risk Counties: Suffolk, Essex, Plymouth, Middlesex. FEMA estimates nearly 15% of properties in Revere fall within VE or AE zones.
Historic Flood Events:
1996 & 2010 Eastern Mass Floods: Lawrence and Methuen saw major sewer system failures and home evacuations.
Boston Nor’easters (2018): Record coastal flooding from tidal surge.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly recommended for homes in coastal cities (Revere, Quincy, Boston’s waterfronts), and older urban centers like Lowell, Lawrence, and Chelsea. Homes built before 1970 with floor drains or basement-level fixtures should be prioritized for installation.
Overview: Surrounded by four of the five Great Lakes, Michigan faces flood risks from shoreline erosion, storm surge, and inland river overflow. Urban flooding is a growing concern, especially in older cities like Detroit and Flint where combined sewer systems are common.
Primary Flood Zones: AE zones dominate along Lake Michigan, Lake Erie, and major rivers like the Grand, Rouge, and Clinton. AO zones are common in low-lying neighborhoods of Detroit and Saginaw.
Localized Hotspots:
Detroit (Wayne County): AO and AE zones in Jefferson Chalmers, Dearborn, and Southwest Detroit. Backups due to aging CSOs.
Grand Rapids (Kent County): AE zones along the Grand River and Plaster Creek.
Saginaw and Flint: AE and AO zones in older neighborhoods with poor drainage.
High-Risk Counties: Wayne, Kent, Macomb, Saginaw. Tens of thousands of properties lie in SFHAs, particularly in southeast Michigan.
Historic Flood Events:
2021 Southeast Michigan Flood: 6+ inches of rain in hours led to 46,000 insurance claims and mass sewer overflows.
2013 Grand Rapids Flood: Record river levels displaced hundreds.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical in Detroit and Grand Rapids for homes with below-grade bathrooms. Install in any area where heavy rain regularly overwhelms stormwater capacity.
Overview: Minnesota’s flood risk is shaped by the Mississippi, Red River, and Minnesota Rivers, with additional threats from heavy snowmelt and spring rain. Flash flooding affects southern and southeastern counties, while Fargo-Moorhead faces river flood risks nearly every year.
Primary Flood Zones: AE and A zones are widespread along river basins. AO zones in Minneapolis and St. Paul’s older residential sectors.
Localized Hotspots:
Minneapolis/St. Paul (Hennepin and Ramsey Counties): AO and AE zones near the Mississippi, Minnehaha Creek, and Como Lake.
Mankato and Rochester: AE zones along the Minnesota and Zumbro Rivers.
Moorhead (Clay County): AE zones along the Red River; severe flood history.
High-Risk Counties: Hennepin, Ramsey, Clay, Olmsted. Thousands of homes mapped in SFHAs.
Historic Flood Events:
2009 Red River Flood: Record crest in Moorhead/Fargo area.
2010 Southeast MN Flash Floods: Up to 10 inches of rain in 24 hours.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Recommended for homes near creeks and rivers in the Twin Cities, and essential in Red River Valley communities like Moorhead and Crookston.
Overview: Mississippi is frequently impacted by hurricanes and heavy rain events from the Gulf of Mexico. The Mississippi River and its tributaries also contribute to regular flooding inland. Low-income and rural communities with limited infrastructure are often hardest hit.
Primary Flood Zones: VE and AE zones along the Gulf Coast and Mississippi River. A and AO zones in Jackson, Vicksburg, and Hattiesburg.
Localized Hotspots:
Gulfport and Biloxi (Harrison County): VE and AE zones along the coastline and Bay St. Louis. Many homes still vulnerable from Katrina-era rebuilding.
Jackson (Hinds County): AE and AO zones around the Pearl River. Combined infrastructure and clay-heavy soils contribute to poor drainage.
Vicksburg and Natchez: AE zones along the Mississippi River. Prone to backwater and tributary flooding.
High-Risk Counties: Harrison, Hinds, Forrest, Warren, Hancock. FEMA estimates tens of thousands of homes statewide in SFHAs.
Historic Flood Events:
Hurricane Katrina (2005): Catastrophic flooding in Biloxi and Gulfport. Sewer and drainage infrastructure wiped out.
2020 Pearl River Flood: Jackson neighborhoods evacuated; dozens of homes flooded.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-priority installations in Jackson, Gulfport, and Pascagoula. Emphasize homes with aging sewer lines and no backwater valves in inland towns like Meridian and Laurel.
Overview: Missouri is situated at the confluence of the Mississippi and Missouri Rivers, making it one of the most flood-exposed states in the country. Riverine and flash flooding are common. Cities like St. Louis, Jefferson City, and Springfield are vulnerable due to old sewer systems and proximity to major water bodies.
Primary Flood Zones: AE and A zones are widespread along the Mississippi, Missouri, and Meramec rivers. AO zones appear in flat urban areas and flood-prone suburbs.
Localized Hotspots:
St. Louis (St. Louis County/City): AE zones stretch along the Mississippi and River Des Peres; AO zones affect Dogtown, Dutchtown, and south city neighborhoods.
Jefferson City (Cole County): AE zones around the Missouri River; recurring basement floods from stormwater intrusion.
Springfield and Joplin: AO and AE zones near James River and Shoal Creek; clay-heavy soil and outdated sewers increase risk.
High-Risk Counties: St. Louis, Cole, Greene, Jackson. FEMA data shows significant clusters of flood claims throughout these regions.
Historic Flood Events:
1993 Great Flood: Missouri River breached levees, caused record flooding across the state.
2015 and 2019 Flash Floods: Hit St. Louis metro region. River Des Peres overflowed, flooding streets and homes.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly advised for homes in St. Louis neighborhoods with below-grade bathrooms and floor drains. Also vital in riverfront towns such as Hannibal, Cape Girardeau, and Washington, where combined sewer systems are common.
Overview: Though mountainous, Montana is vulnerable to flash floods, snowmelt-driven flooding, and ice jams. River valleys and basins in the west, and flat prairie in the east, see seasonal flooding that can overwhelm both rural and urban areas.
Primary Flood Zones: AE and A zones along the Missouri, Yellowstone, and Clark Fork Rivers. AO zones appear in low-lying areas of Billings and Missoula.
Localized Hotspots:
Billings (Yellowstone County): AE zones around the Yellowstone River; AO zones in neighborhoods with shallow water tables.
Missoula (Missoula County): AE zones along the Clark Fork and Bitterroot Rivers.
Great Falls and Helena: AE zones along the Missouri River and Sun River confluences.
High-Risk Counties: Yellowstone, Missoula, Cascade, Lewis and Clark. Many floodplain properties are in proximity to tributaries with steep runoff gradients.
Historic Flood Events:
2022 Yellowstone National Park Flood: Destroyed roads and bridges, with downstream impacts in Gardiner and Livingston.
2011 Montana Floods: Snowmelt and rain led to statewide damages exceeding $50 million.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Priority installations for homes in Billings, Missoula, and river basin towns with aging stormwater or septic systems.
Overview: Nebraska experiences frequent river flooding from the Missouri, Platte, and Elkhorn Rivers. Flash flooding and ice jams are common during snowmelt. Urban flooding affects Omaha and Lincoln.
Primary Flood Zones: AE zones along river corridors. AO zones appear in suburban developments around Omaha.
Localized Hotspots:
Omaha (Douglas County): AE zones in Florence and Carter Lake. AO zones near Papillion Creek.
Lincoln (Lancaster County): AO and AE zones near Salt Creek and Antelope Valley.
Fremont and Bellevue: AE zones along the Platte River and Offutt Air Force Base.
High-Risk Counties: Douglas, Lancaster, Dodge, Sarpy. Nebraska saw over 4,000 flood insurance claims in 2019 alone.
Historic Flood Events:
2019 Central Plains Floods: Worst flooding in state history. Hundreds of homes destroyed, particularly in Fremont and surrounding areas.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly recommended for homes near rivers and drainage channels in Omaha and Lincoln. Rural properties near levees and agricultural ditches are also vulnerable.
Overview: Though arid, Nevada experiences significant flash flooding from summer monsoons, particularly in Las Vegas Valley and the Reno-Carson corridor. Burn scars and desert pavement increase runoff and flood velocity.
Primary Flood Zones: AO and AE zones appear in Las Vegas and Reno. Washes and channels funnel water rapidly in flash flood events.
Localized Hotspots:
Las Vegas (Clark County): AO zones throughout valley neighborhoods. AE zones near Flamingo Wash and Tropicana Wash.
Reno (Washoe County): AE zones along the Truckee River; floodwalls mitigate some risk.
Carson City: AE zones around Kings Canyon and Eagle Valley.
High-Risk Counties: Clark, Washoe, Carson City.
Historic Flood Events:
1997 Truckee River Flood: $600 million in damages in Reno.
2010–2023 Periodic Monsoon Floods: Annual urban flooding in Las Vegas suburbs.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Crucial in Las Vegas neighborhoods with slab-on-grade construction, and for homes in Reno’s low-elevation zones.
Overview: Flooding in New Hampshire arises from both inland river overflow and storm surge along the 18-mile coastline. Key river systems include the Merrimack, Connecticut, Saco, and Piscataqua. Ice jams and snowmelt floods are also prevalent.
Primary Flood Zones: Zone AE dominates river valleys; Zone VE occurs in Hampton, Rye, and Seabrook along the coast. Zone AO is common in older, urbanized areas like Manchester and Nashua where shallow ponding occurs during intense rain events.
Localized Hotspots:
Manchester (Hillsborough County): AO and AE zones along the Merrimack River and in West Side neighborhoods.
Nashua (Hillsborough County): AE zones flank the Nashua and Merrimack Rivers. AO zones appear in industrial corridors.
Seacoast Region (Rockingham County): Hampton Beach, Seabrook, and Portsmouth are prone to tidal and storm surge flooding.
High-Risk Counties: Rockingham (coastal surge), Hillsborough (urban runoff), and Merrimack (riverine flooding). FEMA estimates over 9% of parcels in Rockingham fall within SFHAs.
Historic Flood Events:
2006 Mother’s Day Flood: 15 inches of rain fell across southern NH. Over 600 homes flooded in Rockingham and Hillsborough counties.
October 2005 Floods: Nashua and Keene suffered major sewer system failures.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-priority zones include East and South Manchester, Nashua’s Crown Hill and Tree Streets neighborhoods, and the coastal towns of Hampton and Seabrook. Installations should be emphasized in homes built pre-1970 and commercial buildings with below-grade plumbing.
Overview: New Jersey’s exposure to tidal surge from the Atlantic Ocean and rainfall-induced river flooding makes it one of the most flood-prone states. Dense urban infrastructure compounds the problem—many municipalities operate under combined sewer systems, especially in older cities. Coastal areas like Atlantic City and inland cities like Paterson face drastically different yet equally serious flood threats.
Primary Flood Zones: Zones AE and VE are heavily present along the coast and tidal back bays. AO zones occur in cities like Newark, Jersey City, and Hoboken. AE zones stretch up the Passaic, Raritan, and Delaware River valleys.
Localized Hotspots:
Hoboken and Jersey City (Hudson County): AO and AE zones are prevalent. Combined sewer systems and high building density make these cities prime candidates for early detection technology.
Newark (Essex County): AO zones occur in Ironbound and South Ward neighborhoods, where rainfall and tidal backflow often coincide.
Passaic County (Paterson): AE zones around the Passaic River. Historically vulnerable due to stormwater runoff and overwhelmed sanitary sewers.
South Jersey Shore (Atlantic, Ocean Counties): VE zones across Atlantic City, Ventnor, Brigantine. AE zones inland where barrier island floodwaters collect.
High-Risk Counties: Hudson, Essex, Bergen, Passaic, Atlantic, and Ocean. According to state data, over 80,000 residential properties lie in SFHAs, with thousands more at risk under extreme weather scenarios.
Historic Flood Events:
Hurricane Sandy (2012): Caused $30 billion in damage in NJ. Coastal and inland areas experienced record flooding. Hoboken lost power and sewer access for days.
Hurricane Irene (2011): Inland rivers like the Raritan and Passaic overtopped banks. Multiple municipalities declared emergencies due to sewer and stormwater backups.
2007 Nor’easter: Rainfall of 8–10 inches across North Jersey caused massive CSO discharges and street-level flooding in Newark, Paterson, and Elizabeth.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strong recommendation for use in Hoboken, Newark, Jersey City, Paterson, and Bayonne. Coastal towns like Longport, Margate, and Toms River should be targeted for homes with ground-level bathrooms or finished basements. For homeowners in both urban and beach areas, SewerAlarm provides real-time defense against backup-related damage.
Overview: New Mexico’s flood threats arise from monsoonal rains, snowmelt in mountainous regions, and dry arroyos that channel sudden deluges. Urban centers like Albuquerque and Santa Fe see sewer overload and runoff issues.
Primary Flood Zones: AE and A zones occur near the Rio Grande and Pecos River. AO zones dominate in Albuquerque.
Localized Hotspots:
Albuquerque (Bernalillo County): AO zones near Tijeras Arroyo and North Valley. AE zones near the Rio Grande.
Santa Fe (Santa Fe County): AO zones in historic neighborhoods with narrow runoff paths.
Las Cruces: AE zones along the Rio Grande and in low-lying areas.
High-Risk Counties: Bernalillo, Dona Ana, Santa Fe, San Juan.
Historic Flood Events:
2006 Santa Fe Flood: 6 inches of rain caused widespread flash floods.
2010 Albuquerque Floods: Sewer overflows and arroyo flash floods damaged dozens of properties.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-priority for older homes with shallow utility access in Albuquerque’s valley neighborhoods and in Santa Fe’s eastside subdivisions.
Overview: New York’s vast and varied landscape includes coastal areas vulnerable to storm surge, river valleys prone to overflow, and dense urban centers with aged sewer infrastructure. From the flood-prone streets of Queens to the riverfronts of the Hudson Valley and the creeks of Western New York, nearly every region in the state is exposed to flood risk. New York City alone is home to millions living in or near SFHAs (Special Flood Hazard Areas), many in buildings with basement plumbing highly susceptible to sewer backup.
Primary Flood Zones: Zones AE, A, VE, and AO are all prevalent. VE zones dominate coastal communities along Long Island and Staten Island. AO zones are common in Queens, Brooklyn, and the Bronx. AE zones are widespread along the Hudson, Mohawk, and Genesee rivers.
Localized Hotspots:
New York City (NYC):
Queens (Jamaica Bay, Flushing, and Rockaways): AE and AO zones coincide with CSOs and outdated plumbing infrastructure. Many homes and apartments with basement-level fixtures experience backups during moderate rain.
Staten Island (East Shore, Midland Beach): VE and AE zones dominate. Hurricane Sandy led to major buyout programs in Oakwood Beach.
Bronx (Westchester Creek, Hutchinson River): AE zones in low-lying neighborhoods like Soundview.
Brooklyn (Gowanus Canal, Red Hook): AO and AE zones flood regularly; combined sewer infrastructure is aging and under stress.
Hudson Valley (Ulster, Dutchess, Orange Counties): AE zones line the Hudson River and smaller tributaries like the Esopus Creek.
Western NY (Buffalo, Erie County): AE and AO zones near Buffalo River and Scajaquada Creek, particularly in neighborhoods like Kaisertown and Black Rock.
High-Risk Counties: Kings, Queens, Richmond, Bronx, New York, Erie, Westchester, Orange, Suffolk, and Nassau. According to FEMA, over 400,000 properties in NYC alone lie within designated flood zones.
Historic Flood Events:
Hurricane Sandy (2012): Over 44 deaths in NYC. 100,000+ homes and businesses flooded. Critical sewer infrastructure overwhelmed.
Hurricane Ida (2021): Flash flooding in NYC caused at least 13 deaths, mostly in basement apartments. Sewer systems across the boroughs failed.
2006 Mohawk River Flooding: Flooded entire downtown Oneonta and parts of Schenectady. Sewer backups widely reported.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High urgency in all five NYC boroughs, especially Queens, Brooklyn, and the Bronx. Focus on homes with basement units or old combined sewer systems. Essential in Hudson Valley towns along the Wallkill and Esopus Rivers and in Buffalo neighborhoods near the waterfront.
Overview: North Carolina is exposed to major hurricanes, riverine flooding, and flash floods due to both its coastal location and mountainous west. Cities like Wilmington, Fayetteville, and Asheville all face distinct flood risks tied to geography and infrastructure age.
Primary Flood Zones: VE zones dominate barrier islands and Cape Fear region. AE and A zones trace the Neuse, Tar, Cape Fear, and French Broad Rivers. AO zones appear in flat urban areas like Raleigh and Fayetteville.
Localized Hotspots:
Wilmington (New Hanover County): AE and VE zones along the Cape Fear River and Intracoastal Waterway.
Fayetteville (Cumberland County): AE zones along the Cape Fear River floodplain; AO zones in downtown and older subdivisions.
Asheville (Buncombe County): AE zones along the Swannanoa River and French Broad. Flash flooding occurs after heavy mountain rainfall.
High-Risk Counties: New Hanover, Cumberland, Craven, Pitt, Mecklenburg. FEMA estimates over 200,000 structures at risk statewide.
Historic Flood Events:
Hurricane Florence (2018): Dropped 20+ inches of rain. Devastated Lumberton, Wilmington, and Kinston.
Hurricane Matthew (2016): Caused record flooding in eastern NC; overwhelmed sewer systems in Fayetteville and Goldsboro.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Recommended for homes near floodplain zones in Fayetteville, Wilmington, and eastern towns like Kinston and Lumberton. Also beneficial in Asheville and Boone where rapid runoff leads to basement flooding.
Overview: North Dakota's flood risks are dominated by riverine flooding from the Red River of the North, Souris River, and Missouri River systems. Flat topography in the Red River Valley contributes to slow-draining, widespread floods. Spring snowmelt and ice jams exacerbate seasonal risk.
Primary Flood Zones: AE and A zones dominate the Red River and Souris River basins. Fargo, Grand Forks, and Minot are particularly vulnerable.
Localized Hotspots:
Fargo (Cass County): AE zones along the Red River. AO zones in older residential neighborhoods east of downtown.
Grand Forks (Grand Forks County): AE zones near the Red River and English Coulee.
Minot (Ward County): AE zones along the Souris River, particularly the valley floor near Broadway and Roosevelt Park.
High-Risk Counties: Cass, Grand Forks, Ward. The majority of flood insurance claims in North Dakota come from these counties.
Historic Flood Events:
1997 Red River Flood: Forced mass evacuations in Grand Forks. Over 50,000 residents displaced.
2011 Minot Flood: Souris River reached record levels. Over 4,000 homes flooded.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential for properties along the Red River in Fargo and Grand Forks, especially older homes with basement systems. Also critical in Minot neighborhoods within the Souris floodplain.
Overview: Ohio’s flood risk is driven by the Ohio River, Lake Erie, and extensive interior river systems like the Scioto, Cuyahoga, and Great Miami. The state also has dense urban centers with outdated sewer systems and clay-heavy soil, increasing infiltration risk.
Primary Flood Zones: AE and A zones along rivers and near the Lake Erie shoreline. AO zones in older industrial cities.
Localized Hotspots:
Cincinnati (Hamilton County): AE zones along the Ohio River and Mill Creek floodplain.
Columbus (Franklin County): AE and AO zones near the Scioto and Olentangy Rivers.
Cleveland (Cuyahoga County): AO zones near Big Creek and the Lake Erie shoreline.
High-Risk Counties: Hamilton, Franklin, Cuyahoga, Lucas. FEMA maps show thousands of properties in SFHAs across metro areas.
Historic Flood Events:
1937 Ohio River Flood: One of the deadliest in state history.
2004 and 2008 Urban Floods: Columbus and Cincinnati suffered major sewer backups.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly recommended for homes with basements in Cincinnati, Columbus, and Cleveland. Especially urgent in CSO neighborhoods and riverfront housing.
Overview: Although landlocked, Oklahoma is vulnerable to both flash flooding and riverine flooding. Its wide range of terrain—plains, hills, and valleys—combined with heavy thunderstorms and tropical remnants, results in fast-rising water events. Older cities with aging infrastructure are particularly susceptible to sewer backup during floods.
Primary Flood Zones: AE and A zones run along the Arkansas, Canadian, and Cimarron rivers. AO zones are mapped in flat or urbanized areas of Tulsa and Oklahoma City.
Localized Hotspots:
Oklahoma City (Oklahoma County): AO and AE zones dominate areas near North Canadian River, including neighborhoods like Capitol Hill and Stockyards City.
Tulsa (Tulsa County): AE zones along the Arkansas River and Mingo Creek; frequent flooding has led to extensive floodplain management efforts.
Muskogee and Norman: AE zones span portions of the Verdigris and Canadian River systems.
High-Risk Counties: Tulsa, Oklahoma, Cleveland, Muskogee. FEMA has mapped thousands of parcels within SFHAs in metro and river-adjacent areas.
Historic Flood Events:
1984 Memorial Day Flood in Tulsa: Killed 14 people and caused over $180 million in damages.
2019 Spring Floods: Arkansas River overflowed into Tulsa neighborhoods, leading to dozens of sewer-related basement incidents.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical for older homes in Tulsa and Oklahoma City within proximity to rivers, creeks, and known AO zones. Installations especially needed in pre-1975 homes lacking modern floodproofing or sump pumps.
Overview: Oregon faces flooding from coastal storms, snowmelt, and saturated soils during persistent winter rain. Rivers like the Willamette, Rogue, and Umpqua regularly overflow.
Primary Flood Zones: AE zones dominate floodplains. AO zones in urban Portland and Eugene.
Localized Hotspots:
Portland (Multnomah County): AE and AO zones along Johnson Creek, Columbia Slough, and Sellwood neighborhood.
Eugene and Springfield: AE zones along the Willamette River.
Medford and Grants Pass: AE zones on the Rogue River.
High-Risk Counties: Multnomah, Lane, Jackson, Marion.
Historic Flood Events:
1996 Willamette Valley Floods: Portland and surrounding towns heavily damaged.
2012 Rogue River Flood: Major overflow impacted southwest Oregon towns.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Install in basement-equipped Portland homes, particularly east of 82nd Ave. Critical for homes in Eugene floodplain neighborhoods with shallow lot grading.
Overview: While Pennsylvania lacks a coastal border, its flood risk is substantial due to its extensive network of rivers and older urban infrastructure. The state has over 83,000 miles of rivers and streams, making it especially vulnerable to inland flooding from heavy rainfall, snowmelt, and tropical remnants. Cities like Philadelphia, Pittsburgh, and Harrisburg also face sewer backup risks due to combined storm and sanitary systems.
Primary Flood Zones: AE and A zones dominate floodplain areas along the Susquehanna, Schuylkill, and Delaware Rivers. AO zones are present in flat areas of urban cities like Harrisburg and Reading.
Localized Hotspots:
Philadelphia (Philadelphia County): AO and AE zones in neighborhoods like Eastwick, Germantown, and Manayunk. Cobbs Creek and Tacony Creek pose backup risks for properties with basement plumbing.
Pittsburgh (Allegheny County): AE zones around the Allegheny, Monongahela, and Ohio Rivers. Runoff from steep hills often overwhelms combined sewers.
Harrisburg and Steelton (Dauphin County): AE zones along the Susquehanna River; AO zones in older neighborhoods with narrow stormwater channels.
High-Risk Counties: Philadelphia, Allegheny, Dauphin, Luzerne, Lackawanna, Lancaster. FEMA reports that 5–10% of all structures in Dauphin County fall within an SFHA.
Historic Flood Events:
Hurricane Agnes (1972): Caused $2 billion in damage. Wilkes-Barre saw massive flooding along the Susquehanna River.
2006 Floods: Brought extensive sewer overflows and basement flooding to Luzerne, Schuylkill, and Berks counties.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Critical for properties near the Susquehanna River basin (Harrisburg, Wilkes-Barre), steep-hilled Pittsburgh neighborhoods, and Philadelphia homes with aging infrastructure and below-grade bathrooms.
Overview: Despite its small size, Rhode Island’s complex network of bays, rivers, and urban density puts much of the state at risk for both coastal and inland flooding. The Pawtuxet, Blackstone, and Woonasquatucket rivers regularly overflow during major storms.
Primary Flood Zones: Zone VE dominates the edges of Narragansett Bay. AE zones are common along inland river corridors in Warwick, Cranston, and Providence. AO zones appear in urban flatlands such as Olneyville and Pawtucket’s downtown.
Localized Hotspots:
Providence (Providence County): AO and AE zones near the Woonasquatucket River, South Providence, and Silver Lake neighborhoods.
Warwick (Kent County): AE zones along the Pawtuxet River and Buttonwoods area. Past FEMA buyouts occurred here.
Cranston and Pawtucket: Combined sewer overflow infrastructure makes these ideal candidates for early warning technology.
High-Risk Counties: Providence and Kent counties lead the state in SFHA designations.
Historic Flood Events:
March 2010 Floods: Worst in state history. Warwick received 15 inches of rain in one month. Over 5,000 homes damaged. Sewer systems in Cranston and Pawtucket overwhelmed.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Priority areas include all homes near the Pawtuxet River, downtown Providence, West Warwick, and Edgewood. SewerAlarm is especially critical in homes with below-grade fixtures built before 1985.
Overview: South Carolina's flood risk stems from hurricanes, tropical rainfall, and tidal rivers. Cities like Charleston and Myrtle Beach are extremely vulnerable to storm surge. Inland areas experience prolonged riverine flooding during hurricane season.
Primary Flood Zones: VE and AE zones are widespread along the coast and inland tidal rivers. AO zones are mapped in parts of Columbia, North Charleston, and Summerville.
Localized Hotspots:
Charleston (Charleston County): AE and VE zones throughout the peninsula and West Ashley. Drainage problems amplify sewer backup risks.
Columbia (Richland County): AE zones along the Congaree River. AO zones in low-lying urban neighborhoods.
Georgetown and Horry Counties: AE zones along the Waccamaw and Pee Dee Rivers.
High-Risk Counties: Charleston, Horry, Richland, Georgetown, Berkeley. Charleston County alone has over 100,000 residents in flood zones.
Historic Flood Events:
2015 South Carolina Flood: Caused by 1,000-year rainfall. Over 20 dams breached and 19 people killed.
Hurricane Hugo (1989): Historic storm surge in Charleston.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Must-have for Charleston homes with ground-level plumbing. Critical in Columbia’s historic neighborhoods and Myrtle Beach’s beachfront zones.
Overview: South Dakota experiences both riverine and flash flooding. Risk is highest along the Missouri River and its tributaries. Rapid City has a particularly tragic flood history. The state's rural character often means fewer defenses against floodwater infiltration.
Primary Flood Zones: AE and A zones along the Missouri, James, and Big Sioux Rivers. AO zones in Rapid City and Sioux Falls.
Localized Hotspots:
Sioux Falls (Minnehaha County): AE zones around Big Sioux River. AO zones in central city neighborhoods near ravines.
Rapid City (Pennington County): AO zones in Canyon Lake and Meadowbrook; AE zones along Rapid Creek.
Pierre and Yankton: AE zones along the Missouri River.
High-Risk Counties: Minnehaha, Pennington, Hughes, Yankton. Many flood-prone properties lie near undeveloped drainage basins.
Historic Flood Events:
1972 Rapid City Flood: Deadliest flood in SD history. 238 deaths. Massive infrastructure damage.
2011 Missouri River Flood: Forced levee breaches and widespread flooding.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Vital for older homes in Rapid City and Sioux Falls, especially those with basements or crawlspaces near floodways.
Overview: Tennessee’s flood risk is tied to its geography—Appalachian highlands, the Cumberland Plateau, and major river systems like the Tennessee and Cumberland Rivers. Urban flash flooding, especially in Nashville and Memphis, is a growing concern due to aging infrastructure and high runoff from heavy storms.
Primary Flood Zones: AE and A zones are present throughout the Tennessee River watershed. AO zones are found in urban areas like Nashville and Chattanooga.
Localized Hotspots:
Nashville (Davidson County): AE and AO zones along Mill Creek, Richland Creek, and the Cumberland River. Historic neighborhoods like East Nashville and Bellevue are at high risk.
Memphis (Shelby County): AE zones along the Mississippi River and Nonconnah Creek. AO zones in older subdivisions near midtown and Raleigh.
Chattanooga (Hamilton County): AE zones along the Tennessee River and AO zones in downtown neighborhoods near flood-prone infrastructure.
High-Risk Counties: Davidson, Shelby, Hamilton, Montgomery, Sumner.
Historic Flood Events:
2010 Nashville Flood: Over 13 inches of rain in two days led to $2 billion in damage and 11 deaths. Major sewer failures.
2021 Waverly Flood: Flash flooding killed 20 people in Humphreys County. Over 17 inches of rain fell in 24 hours.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Urgently needed in Nashville neighborhoods with historic sewer systems, especially areas with finished basements or below-grade bathrooms. Also recommended for Memphis and Chattanooga homes near known floodways or drainage bottlenecks.
Overview: Texas faces nearly every type of flooding hazard: coastal surge, riverine flooding, flash floods in Hill Country, and urban flooding in rapidly growing metro areas like Houston, Dallas, and Austin. The vast size and geographic diversity make flood preparation essential statewide.
Primary Flood Zones: VE zones dominate Gulf Coast cities. AE and A zones appear along the Trinity, Brazos, and Guadalupe rivers. AO and AH zones appear in older neighborhoods of Houston and San Antonio.
Localized Hotspots:
Houston (Harris County): AO, AE, and AH zones across the city. Buffalo Bayou and Brays Bayou overflow frequently. Many neighborhoods lack modern drainage.
Austin and San Antonio: AO zones in Onion Creek (Austin) and Leon Creek (San Antonio).
Beaumont and Galveston: VE and AE zones along Sabine Lake and the Gulf. Low elevation and storm surge threats.
High-Risk Counties: Harris, Fort Bend, Galveston, Jefferson, Bexar, Travis. Texas has more properties in flood zones than any state except Florida.
Historic Flood Events:
Hurricane Harvey (2017): Dumped over 50 inches of rain in parts of Houston. Over 200,000 homes flooded. Major CSO and backup failures.
2015 and 2016 Central Texas Floods: Flash flooding across Hill Country, Austin, and Dallas.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly recommended for homes in Houston’s inner loop, Meyerland, Greenspoint, and other historic flood zones. Needed in low-lying homes across southeast Texas with slab-on-grade construction or aging drainage.
Overview: Utah experiences flooding from monsoon storms, snowmelt, and isolated cloudbursts. The state’s many canyons, washes, and alluvial fans contribute to rapid water movement and flash flooding.
Primary Flood Zones: AE and A zones in valleys and along the Weber, Jordan, and Virgin Rivers. AO zones in suburbs of Salt Lake City and St. George.
Localized Hotspots:
Salt Lake City (Salt Lake County): AE zones in Sugar House and Glendale; AO zones in low-lying basins.
St. George (Washington County): AO zones in Santa Clara and AE zones along the Virgin River.
Logan and Ogden: AE zones along the Logan and Ogden Rivers.
High-Risk Counties: Salt Lake, Washington, Cache, Weber.
Historic Flood Events:
1983 Salt Lake Flood: Water overflowed storm drains and caused downtown damage.
2005 St. George Flood: Destroyed homes along the Virgin River.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Recommended in Salt Lake, Ogden, and St. George for homes with below-grade plumbing in neighborhoods with shallow drainage.
Overview: Vermont's topography, characterized by steep hillsides, narrow valleys, and winding rivers, makes it especially susceptible to flash floods. The state’s flood risk peaks in spring (from snowmelt) and late summer (from tropical systems). The Winooski, White, and Otter Creek rivers are frequent contributors to inundation in low-lying areas.
Primary Flood Zones: FEMA maps show widespread AE zones along river corridors. Zones A and AO exist in urban centers like Montpelier and Barre. AE zones follow the Winooski, Connecticut, Lamoille, and White Rivers, particularly in towns such as Waterbury, Bethel, and Hardwick.
Localized Hotspots:
Montpelier (Washington County): AE zone spans the downtown corridor along the Winooski River. Multiple businesses and homes with basement-level plumbing are vulnerable.
Brattleboro (Windham County): AE zones cluster around the West River and downtown lowlands. Combined sewer systems increase sewer backup risk.
Barre and Northfield (Washington County): Historical flooding caused by river overflow and runoff from steep terrain.
High-Risk Counties: Windsor, Windham, Washington, and Orange counties. FEMA designates over 11% of structures in Windsor County within a Special Flood Hazard Area.
Historic Flood Events:
1927 Vermont Flood: Still considered one of the worst in state history—killed 84 people.
Tropical Storm Irene (2011): Caused over $700 million in damage. Over 500 miles of roads and 200 bridges destroyed. Barre and Waterbury were among the hardest-hit towns.
July 2023 Flooding: 9 inches of rain over two days. Montpelier experienced catastrophic downtown flooding, with water breaching storefronts and inundating basements.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Prioritize installations in Montpelier, Barre, Brattleboro, White River Junction, and low-lying areas of Rutland and Woodstock. Ideal for homes built before 1980 with basement floor drains or in towns with combined sewer overflows (CSOs).
Overview: Virginia’s flood risk is shaped by its varied topography—ranging from Appalachian mountain streams to Chesapeake Bay tidal basins and the Atlantic coast. Urban flooding, tidal surge, and flash floods all occur throughout the state. Coastal cities like Norfolk and Hampton Roads are among the most flood-prone in the country due to rising sea levels and subsidence.
Primary Flood Zones: VE and AE zones dominate the coastline and bayfront areas. AO zones are concentrated in older sections of Norfolk, Richmond, and Roanoke. A zones follow river corridors across the Blue Ridge and Shenandoah regions.
Localized Hotspots:
Norfolk and Virginia Beach: VE and AE zones along the Elizabeth River, Lafayette River, and Oceanfront. Frequent nuisance and flash flooding has made Norfolk a focus of national resilience studies.
Richmond (Henrico County): AE zones near the James River. AO zones in older neighborhoods like Shockoe Bottom and Southside.
Roanoke and Salem: A zones along the Roanoke River and Tinker Creek. Frequent flash flooding due to steep terrain and heavy summer rains.
High-Risk Counties: Norfolk City, Virginia Beach, Richmond, Roanoke, Fairfax, Arlington, and Prince William. FEMA identifies over 400,000 Virginians living in SFHAs.
Historic Flood Events:
Hurricane Isabel (2003): One of the most damaging in state history—storm surge reached 8 feet in some coastal cities.
2016 Rain Events in Roanoke: Dropped over 7 inches in 12 hours, flooding over 500 basements.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Essential for homes in Norfolk, Virginia Beach, and Richmond near riverfront zones. Older homes in Roanoke with basement floor drains should be prioritized.
Overview: Western Washington’s flood risk stems from heavy rainfall, snowmelt, and river overflow, especially from the Skagit, Snohomish, and Chehalis Rivers. Coastal surge and saturated soils also increase flood hazards.
Primary Flood Zones: AE zones in river valleys and near Puget Sound. AO zones in Seattle’s older neighborhoods.
Localized Hotspots:
Seattle (King County): AO and AE zones in Georgetown, South Park, and Ballard.
Tacoma and Everett: AE zones near Commencement Bay and Snohomish River.
Chehalis and Centralia: AE zones along Chehalis River floodplain.
High-Risk Counties: King, Snohomish, Lewis, Pierce.
Historic Flood Events:
2007 Chehalis Flood: Major I-5 closure and hundreds of homes damaged.
2015 Winter Storms: Overflowed rivers across western WA.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: High-priority in Seattle neighborhoods with combined sewer overflows and in riverfront communities across western Washington.
Overview: Mountainous West Virginia is highly prone to flash flooding. Narrow valleys, steep slopes, and aging stormwater infrastructure make the state vulnerable to fast-rising water events following storms or snowmelt.
Primary Flood Zones: Zones A and AE dominate riverine areas and small stream corridors. AO zones are less common but present in some urban areas like Charleston and Huntington.
Localized Hotspots:
Charleston (Kanawha County): AE zones along the Elk and Kanawha Rivers. AO zones in South Hills and Kanawha City neighborhoods.
Beckley and Welch: Prone to flash flooding from small mountain tributaries.
Clendenin and White Sulphur Springs: Severely impacted in the 2016 floods.
High-Risk Counties: Kanawha, Greenbrier, Raleigh, Nicholas, Fayette. Over 8% of structures in Greenbrier County fall in mapped flood zones.
Historic Flood Events:
2016 West Virginia Floods: A 1,000-year rain event that killed 23 people and damaged 1,200+ homes. Greenbrier County was hit hardest.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Priority for homes in Charleston, Clendenin, and flood-prone hollows across the Appalachian Plateau. Especially critical in homes with aging infrastructure and minimal drainage.
Overview: Wisconsin’s flood risk comes from spring snowmelt, riverine overflow, and Great Lakes shoreline storms. Northern and western parts of the state experience flash flooding from heavy rain and hilly terrain. Milwaukee, with its combined sewer system, also experiences chronic flooding.
Primary Flood Zones: AE zones trace the Wisconsin, Mississippi, and Fox Rivers. AO zones are present in older sections of Milwaukee and Madison.
Localized Hotspots:
Milwaukee (Milwaukee County): AO and AE zones near the Menomonee and Kinnickinnic Rivers. Sewer overflow and basement backups are frequent.
Madison (Dane County): AE zones around Lake Monona and Yahara River; flooding impacts low-lying urban homes.
La Crosse and Eau Claire: AE zones along the Mississippi and Chippewa Rivers.
High-Risk Counties: Milwaukee, Dane, La Crosse, Brown. FEMA identifies flood risks for thousands of properties statewide.
Historic Flood Events:
2008 and 2018 Midwest Floods: Extensive damage in southern and western Wisconsin.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Strongly advised in Milwaukee and Madison homes built pre-1970, and in riverside towns where basement backups are common.
Overview: Wyoming is largely mountainous and rural, but still experiences seasonal floods from snowmelt, severe storms, and ice jams. Flash floods in dry canyons are also dangerous.
Primary Flood Zones: AE and A zones are found along the North Platte, Green, and Big Horn Rivers. AO zones in flatter towns like Casper and Riverton.
Localized Hotspots:
Casper (Natrona County): AE zones along the North Platte River and AO zones in western suburbs.
Cheyenne and Laramie: AE zones in low-lying areas near Crow Creek and Laramie River.
Jackson: AE zones in the Snake River Valley.
High-Risk Counties: Natrona, Teton, Laramie, Fremont.
Historic Flood Events:
2011 Spring Snowmelt Floods: Major damage in Fremont County and around Riverton.
1984 Green River Flood: Caused extensive property loss in western Wyoming.
FEMA Map Access: FEMA Flood Map Center
SewerAlarm Recommendation: Advisable for homes with basements or low-lying plumbing in Casper, Riverton, and Jackson.
Final Thoughts
Flooding is not just a coastal or seasonal issue, it is a nationwide threat that affects homeowners in every state, often with little warning and devastating consequences. This guide was built to empower residents, professionals, and policymakers with region-specific insight into flood-prone areas and infrastructure vulnerabilities. Whether you live in a low-lying coastal zone, a midwestern river basin, or a hillside prone to flash floods, the risk of sewer backups during flooding events is real, and preventable. SewerAlarm is committed to early detection and peace of mind. By understanding your local flood profile and proactively installing SewerAlarm in vulnerable properties, you can protect your home, your tenants, and your community from avoidable damage.
References
- Federal Emergency Management Agency (FEMA). Flood Insurance Rate Maps (FIRMs)
- FEMA. National Flood Hazard Layer (NFHL) Viewer
- FEMA. Flood Zones Defined
- United States Geological Survey (USGS). Flood Monitoring and Streamflow Data
- National Oceanic and Atmospheric Administration (NOAA). National Weather Service Flood Safety Resources
- Environmental Protection Agency (EPA). SepticSmart Program
- American Society of Civil Engineers (ASCE). Infrastructure Report Card: Stormwater and Wastewater Sections
- U.S. Census Bureau. Geography and Housing Characteristics Data
- State Emergency Management Agencies and Department of Environmental Protection websites (consulted per state for flood history and mitigation plans)
- SewerAlarm Internal Field Data and Regional Plumber Interviews (2024–2025 Pre-Launch Test Market)