Protecting Your Property from Flooding ...
Sewer Backflow Valves
Are You at Risk?
If you aren't sure whether your house is at risk
from flooding, check with your local floodplain manager, building
official, city engineer, or planning and zoning administrator. They can
tell you whether you are in a flood hazard area. Also, they usually can
tell you how to protect yourself and your house and property from
What You Can Do
Flood protection can involve a variety of changes to
your house and property -- changes that can vary in complexity and cost.
You may be able to make some types of changes yourself. But complicated or
large-scale changes and those that affect the structure of your house or
its electrical wiring and plumbing should be carried out only by a
professional contractor licensed to work in your state, county, or city.
One example of flood protection is installing a backflow valve to prevent
sewage from backing up into your house. This is something that only a
licensed plumber or contractor should do.
Install Sewer Backflow Valves
some floodprone areas, flooding can cause sewage from sanitary sewer lines
to back up into houses through drain pipes. These backups not only cause
damage that is difficult to repair but also create health hazards.
A good way to protect your house from sewage backups
is to install backflow valves, which are designed to block drain pipes
temporarily and prevent flow into the house. Backflow valves are available
in a variety of designs that range from the simple to the complex. The
figure shows a gate valve, one of the more complex designs. It provides a
strong seal, but must be operated by hand. So the effectiveness of a gate
valve will depend on how much warning you have of impending flooding.
Among the simpler valves are a flap or check valves, which open to allow
flow out of the house but close when the flow reverses. These valves
operate automatically but do not provide as strong a seal as a gate valve.
Keep these points in mind if you have backflow
Changes to the plumbing in your house must be
done by a licensed plumber or contractor, who will ensure that the
work is done correctly and according to all applicable codes. This is
important for your safety.
Some valves incorporate the advantages of both
flap and gate valves into a single design. Your plumber or contractor
can advise you on the relative advantages and disadvantages of the
various types of backflow valves.
Valves should be installed on all pipes that
leave the house or that are connected to equipment that is below the
potential flood level. So valves may be needed on washing machine
drain lines, laundry sinks, fuel oil lines, rain downspouts, and sump
pumps, as well as sewer/septic connections.
If you have a sump pump, it may be connected to
underground drain lines, which may be difficult to seal off.
Having a plumber or contractor install one backflow
valve will cost you about $525 for a combined gate/flap valve or about
$375 for a flap valve. These figures include the cost of excavation and
Other Sources of Information
Protecting Your Home from Flooding, FEMA, 1994
Repairing Your Flooded Home, FEMA-234, 1992
Flood Emergency and Residential Repair Handbook,
Retrofitting Flood-Prone Residential Structures,
Building Utilities from Flood Damage, FEMA -348, 1999
To obtain copies of these and other FEMA documents,
call FEMA Publications at 1-800-480-2520. Information is also available on
the World Wide Web at http://www.fema.gov.
After A Flood-Reclaiming Heirlooms & Other Items From Flood Waters
Coping With A Flood Before, During & After
Ventilating, & Air Conditioning Equipment
Flood Safety Tips
Preparing Your Home For A Hurricane
To Contact Us
Office of Emergency Preparedness Phone Numbers
Emergency Management Agency