HomeMy WebLinkAboutCityofEdinaFloodResilienceFactSheets-03-24-2020_Sanitary backflow preventionFor more information on flood resilience, contact the Engineering Department at 952-826-0371.
1According to HomeAdvisor (2020). Costs to install a backflow preventer (including device) depend on the size and type of system. Note that many insurance companies
offer discounts to homeowners who install sanitary backflow prevention devices.
What is a sanitary backflow prevention device/
backflow valve?
A sanitary backflow prevention device is a valve attached to your
plumbing system. It is designed to prevent overflow waste water
from the City’s sewer system from backing up into your home.
Who needs a sanitary backflow prevention device?
Because sanitary backflow prevention devices can prevent the
significant damage caused by sewer backup, the City of Edina
recommends them for all homes. If you have a newer home a
valve may have been installed during construction. Backflow valves
are usually located in the floor; if you have a sump pump the valve
is likely to be close by.
Note that many insurance companies offer discounts to homeowners
who install sanitary backflow prevention devices. The City
recommends that backflow prevention devices be installed by a
licensed plumber. A permit is required for this installation.
How do sanitary backflow
prevention devices work?
A backflow valve has a flap with small
floaters on both sides that allow the
flap to open and close. Under normal
conditions, the flap is open—allowing
water from your home to flow into the
main sewer system. However, if a large
storm or snowmelt overwhelms the
sewer system, causing water or sewage to
backflow toward the house, the floaters
will close the flap, effectively shutting your
home off from the street sewer system
(see detail above). Once the street sewer
system has a chance to drain and return
to normal functioning, the flap opens again
to discharge waste water. Due to the
potential for clogging, annual inspection of
the device is needed.
Reduces vulnerability
Reduces exposure
COST: $135-$1,0001
Backflow preventer
location Sewer lateral
Sewer main
BASEMENT Water level
House sanitary sewer line
Sanitary backflow
prevention device detail
(Image Credit: Mainline
Backflow Products)
Sanitary backflow prevention devices overview
Actions for Flood Resilient Homes:
Sanitary Backflow Prevention Devices
Before flood action During flood action After flood action
For more information on flood resilience, contact the Engineering Department at 952-826-0371.
Actions for Flood Resilient Homes:
Sanitary Backflow Prevention Devices
Make sure you’re ready for sewer backups …
Backflow prevention devices can function automatically or be operated manually. To protect your home, the valve must be
closed during overload periods—which will vary with the size of the storm, but typically last from 2 to 6 hours. Be aware that
during the time the valve is closed you will not be able to use your plumbing.
Other considerations
• You should have your backflow prevention device
cleaned and checked annually, preferably by the
licensed plumber who installed it.
• To avoid backflow in your home plumbing system,
keep your plumbing free of materials such as
diapers, sanitary napkins, and cigarette butts.
• Backwater from a public sewer system is
hazardous to your health. If sewer water enters
your home, you should hire a licensed and trained
professional cleaning service.
(Top) Image of sewer backup in bathroom, courtesy of https://
blueskyplumbingfl.com/wp-content/uploads/2016/10/sewer-
backup-in-bathroom.jpg
(Right) Sanitary backflow prevention device install; image
courtesy of https://www.flickr.com/photos/69302634@
N02/16327005228/in/photostream/
Sanitary backflow preventer installation