The University of Southern California Foundation for
Cross-Connection Control and Hydraulic Research
(USC-FCCCHR) performed a study in late 2002 and early
2003 to determine the degree of protection against
backflow that is present in today’s homes.
The results are summarized as follows:
9.6% of the homes surveyed had direct
health hazard cross-connections
73% of the homes’ water uses were unprotected
cross-connections
95.7% of the homes had either a direct or indirect
cross-connection to a health hazard
91% of the homes had unprotected hose bibbs
43.6% of the homes had heating/cooling system
health hazard cross-connections
Watts reminds you to check the following common
cross-connections in homes to ensure the
proper protection against backflow:
Toilet
When water leaves the drinking water supply
system and flows into the toilet tank, the water
must be prevented from being drawn back into
the water supply. The water in the toilet tank is
often treated with cleansing chemicals that are
not safe to drink.
An anti-siphon ballcock assembly should be
installed in the toilet tank. This will protect
against backsiphonage. The ball cock can also
serve as a thermal expansion relief device, if
equipped with an auxiliary relief valve. The relief
valve should govern the preset pressure to
80psi or less.
Laundry Sink
To make the laundry sink safe, a hose bibb
vacuum breaker is needed. This is a small,
inexpensive device that simply attaches to the
threaded end of the faucet as with the outside
water faucets (sill cocks). It prevents contaminated
water in the sink from being siphoned
back into the drinking water supply.
Outdoor Faucet
The ordinary garden hose is the most common
way to contaminate the water supply. This can
happen when one end of the hose is attached
to an outdoor faucet (sill cock), and the other
end is connected to an aspirator type bottle,
insecticides or other chemicals in the aspirator
bottle can be siphoned back into the drinking
water supply.
You can easily prevent the possibility of this type
of contamination by installing a hose bibb vacuum
breaker. This is a small, inexpensive device that
simply attaches to a threaded water faucet.
Lawn Irrigation System
Lawn irrigation systems need a vacuum breaker
backflow preventer to protect against lawn and
pesticide chemicals being drawn in from the
lawn and back into the drinking water supply.
Heating/Cooling Systems
A hot water system may be used to heat the
home. You can ensure the protection of the
safe drinking water system by making sure a
dual check with atmospheric vent is installed.
This will protect against stagnant or chemically
treated water from recirculating back into the
water supply.
USC Cross-Connections in Household Plumbing Systems Study
There are a number of potential cross-connections in household plumbing systems that must be protected against backflow. To learn more about these hazards and to download a recent study from USC on cross-connections in household plumbing systems,
Stop Backflow News
Backflow contamination can have hazardous or even fatal results. It is essential that backflow prevention programs be put in place and maintained on an ongoing basis. Stop Backflow news presents many case histories outlining the effects of backflow contamination.
