Flash Flooding and Coastal Storms - NYC Health

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What We Do

At-Risk Populations

Threats

Individuals and Families

Mental Health

Emergency Medication Distribution

Communities and Businesses

Health Care Providers

Emergency Departments


Flash Flooding and Coastal Storms

Flash flooding happens when heavy rainfall overwhelms the sewer system and the amount of water the ground can absorb. The rapid rise of water can quickly flood properties and roadways. Flash flooding can be difficult to predict. It can occur with little warning and its effects can vary greatly across small areas.

Coastal storms, which include hurricanes, nor’easters and tropical storms, can cause severe flooding, strong winds and heavy rain. Strong winds and high waters can create hazards such as falling trees, downed power lines, flying debris and loss of heat, water and power.

Learn more about what to do before, during and after a storm.

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Check on Friends, Relatives and Neighbors

People at High Risk

Help friends, relatives and neighbors to prepare for a storm, and check on them after the storm has passed, if it is safe to do so. People most at risk include those who:

Live in coastal storm evacuation zones

Live in basement apartments

Are age 65 years or older

Are socially isolated

Depend on electric medical equipment like a nebulizer for asthma

Have limited mobility or are unable to leave the house alone

Before a Flood or Storm

Plan for a Hurricane or Flash Flood

Follow these tips so you can react quickly in case of a storm or flash flood:

Sign up for emergency alerts at Notify NYC.

Complete the Ready New York: My Emergency Plan workbook (available in 13 languages and in audio format).

Know Your Zone: Learn whether you live in an area where you may need to evacuate the next time there is a hurricane.

Make a meeting plan and prepare emergency supplies. Read comprehensive flood and storm preparation tips.

Take actions to protect and prepare your property at Rainfall Ready NYC.

For people with disabilities and anyone who might need additional assistance in an emergency, refer to preparedness strategies and inclusive planning tips from NYC Emergency Management and the Mayor’s Office for People with Disabilities.

People who use electric medical equipment should:

Contact their utility provider to register for a priority power restoration program.

Make sure to have charged back-up batteries.

Follow specific coastal storm preparedness steps for durable medical equipment users, dialysis patients and individuals with limited mobility.

People who live in a basement apartment should:

Prepare to move to higher ground during periods of heavy rain

Sign up for Notify NYC’s special basement alerts

During a Flood or Storm

Check on friends, relatives and neighbors. Look out for older adults and people with disabilities anyone who might need additional assistance in an emergency to see if they need help.

During coastal storms, follow evacuation orders. During flash floods, seek higher ground.

Follow Evacuation Orders

If you are asked to evacuate, do so immediately. Be sure to have essentials ready to go:

Grab your Go Bag with your important documents, identification, medication, bottled water, nonperishable food, first aid kit and a battery-operated flashlight and radio.

Bring all medications with you and have contact information for your health providers written down.

Stay with friends or family who live outside the evacuation zones. If you have no other shelter, go to an evacuation center. Call 311 to find your nearest evacuation center and for information about transportation options.

Legal pets and service animals are allowed in all NYC shelters and evacuation centers. Be sure to bring your pet’s license, food, leash, carrier, medication and supplies to clean up after your animal.

Travel safely. Use public transportation to evacuate if possible. When considering your transportation route, be aware that public transportation, including MTA's Access-A-Ride, may shut down hours before the storm arrives.

Following an evacuation order, people with disabilities or other access or functional needs who have no other options to evacuate safely, can request transportation assistance by contacting 311. Depending on your need, you will either be taken to an accessible evacuation center in an accessible vehicle or a hospital outside of the evacuation zone via ambulance. You may not be able to request transportation to a specific address.

Do not drive through water. As little as 6 inches of water can cause a car to stall and loss of control of the vehicle.

If You Do Not Evacuate

Follow directions from officials. Check local news and radio, call 311 (212-639-9675 for Video Relay Service, or TTY: 212-504-4115). If you do not receive instructions to evacuate, choose to stay home against recommendations, or if you are unable to leave your home:

Stay out of basements and move to a higher floor, if you live in a location that is at risk for flooding.

Stay away from windows that may break during strong winds.

If you must go outside, stay away from downed and dangling power lines. Treat all downed lines as if they are live and dangerous.

Do not drive through water. As little as 6 inches may cause you to lose control of the vehicle.

During a Power Outage

In the event of a power outage, follow guidance from NYC Emergency Management on utility disruptions.

If it is hot indoors, go to a cool place with air conditioning, like a friend's house, or call 311 to find a cooling center near you.

If you depend on power for life-sustaining equipment, plan to evacuate to a location with power.

Never use gas stoves, ovens, grills (including charcoal grills), kerosene heaters or propane space heaters to heat your home. Kerosene heaters and propane space heaters are illegal in New York City.

Only use generators outdoors and at least 20 feet away from doors, windows and vents. Always follow the manufacturer’s instructions to prevent carbon monoxide poisoning.

Know What to Do If You Lose Water Service

New York City tap water is safe to drink, including in areas with flooding, unless otherwise reported by City officials. If local authorities inform you that the tap water is unsafe, use your emergency water supplies until instructed otherwise.

If your water service was disrupted, run the tap for at least 30 seconds and until the water runs cold and clear. Replace all ice machine filters and beverage dispenser filters and flush all water lines for five minutes.

Monitor the NYC Department of Environmental Protection for updates on NYC drinking water safety.

After a Flood or Storm

Severe flash floods may make homes uninhabitable. Your home may need cleaning and repairs before it is safe to return.

Proceed with Caution after the Storm

Even when a storm has passed, outdoor activities may still pose dangerous hazards. Moving flood water can sweep people and cars away, and it can contain things that can hurt you or make you sick.

Avoid slippery surfaces, unstable trees and branches, unstable structures, fallen power lines and deep standing water that can cause wound infections, rashes, tetanus and gastrointestinal illness. Call the power company to report fallen power lines and 311 to report unsafe conditions.

If you come in contact with floodwater, wash with soap and clean water, or with sanitizer. Take care of wounds and seek medical attention if necessary.

Get help to lift heavy items.

Avoid dark staircases if possible. Use flashlights when needed.

Secure ladders and use them only on level ground.

Do not climb on roofs or attempt to cut down large branches. Call professionals for these types of jobs.

Do not swim, surf or perform any other activities in pools or at beaches until officials say conditions are safe.

Avoid driving vehicles in flooded areas and be careful around roadway obstructions.

Cleaning After a Flood or Storm

Keep children, pets and people with compromised immune systems away until the area has been cleaned and disinfected. If you’ve recently had COVID-19 or have Long COVID, your immune system may be weakened.

Use protective gear. Contact with floodwater or sewage can make you sick.

Use protective eyewear and waterproof gloves and boots when cleaning or coming in contact with sewage. Do not touch your nose, mouth, eyes or ears.

Consider using a dust mask to avoid swallowing accidental splashes from dirty water and sewage.

Remove standing shallow water. Make sure to dry all objects and surfaces thoroughly to avoid mold growth.

Deep water and extensive flood damage may require professional cleanup and restoration.
Throw away any food (including packaged food) that may have been touched by sewage water.

If fuel is found floating on top of water in a flooded basement, refer to the NYS Department of Environmental Conservation's Guidance on Oil Cleanup for information on cleanup and reporting oil spills. The oil should be removed before the water is pumped out. If the oil is not removed first, the floors and walls will be coated with oil as the water is removed.

Sewage Contamination

To clean indoor areas contaminated by sewage:

To disinfect, wipe surfaces with a bleach solution (half cup of bleach in one gallon of water). Non-bleach sanitizers can also be used.

Warning: Never mix bleach with ammonia or detergents containing ammonia products since dangerous gases may be created. Bleach can damage some materials, so use with caution.

Wash clothes, bedding and other fabrics contaminated with sewage with detergent and water. Dry them thoroughly. Dry clean items that cannot be washed.

To clean outdoor areas contaminated by sewage:

Before doing any work, allow the affected part of the yard to dry out and the sewage to break down.

Treat the affected area with garden lime, a product that speeds the breakdown of materials and reduces odors. You can purchase garden lime at garden supply and home improvement stores.

Keep children and pets out of the yard. Both the sewage and lime can harm their health.

If you grow fruits and vegetables, grow plants in containers — and not in the affected soil – for the next year.

Prevent Carbon Monoxide Poisoning

Carbon monoxide poisoning can occur when portable gasoline-powered generators and other tools are used improperly following severe storms and power outages.

Visit NYC Health: Carbon Monoxide Poisoning for more information.

Prevent Mold Growth

Wet conditions following a flood or storm can cause harmful mold to grow.

Visit NYC Health: Mold to learn how mold affects health and for more information on preventing and removing mold.

Additional Resources

Cleanup Guides:

Basement Flooding and Cleaning Up After a Storm (PDF)

A Field Guide for Flooded Home Cleanup (PDF)

Flood and Storm Preparedness

NYC Emergency Management: Plan for Hazards - Flooding

NYC Department of Environmental Protection: Flood Prevention

NYC Department of Environmental Protection: Combined Sewer Overflows

NYC Department of Environmental Protection: Climate Resiliency

For People with Disabilities

NYC Emergency Management: Disabilities, Access and Functional Needs

Mayor's Office for People with Disabilities: Emergency Preparedness: How to Prepare

Water and Climate

FloodNet: Historical Flooding Data

NYC Department of Environmental Protection: Wait… App for Notifications on When to Use Less Water During Heavy Rain

More Information

Climate and Health

Coastal Storm Preparedness for Durable Medical Equipment Users, Dialysis Patients and Individuals with Limited Mobility

What Hurricane Ida and Superstorm Sandy Taught Us About Flooding and Health