Backflow Hazard Prevention

Your garden hose, kitchen sink sprayer, and sprinkler systems are just a few of the ways chemicals or bacteria could enter your drinking water in your home.

Your Garden Hose - A Potential Danger
Garden hoses, showerheads attached to hoses and kitchen hose sprayers left in the wrong place could contaminate your drinking water. This can happen when the hose end is left submerged in bath water, dish water, or any other contaminated water. Using a sprayer hose attachment outside to apply lawn and garden chemicals could also present a hazard. A sudden drop in pressure inside the water line may cause these contaminants to be sucked back into your home’s drinking water supply.

Pressure may also build up inside a hose left on with a shut-off nozzle attached. Especially if left in the hot sun, high pressure may force poor tasting water inside the house into your home’s plumbing.

Cross Connections - Backflow Hazards
A cross connection is a point in a plumbing system where the drinking water supply is connected, or can be connected, to a non-drinking water source. Examples of potential cross connections are:
  • Boiler systems
  • Fire sprinkler systems
  • Irrigation sprinkler systems
  • Outdoor hose faucets
  • Swimming pools
Backsiphonage
There are 2 types of backflow which may occur at cross connections. The 1st type, called backsiphonage, is caused by a negative or reduced pressure in the water supply line. These incidents are not uncommon and may be the result of accidental construction damage to a pipeline or firefighters battling a nearby fire.

Backpressure
The other type of backflow, called backpressure, may happen whenever the drinking water supply line is connected to another system operating at a higher pressure. Some examples of potential backflow sources:
  • Boiler system
  • Booster pump
  • Other pressurized systems, such as high-rise building water systems
Backflow Prevention - What You Can Do
Inexpensive and easy-to-install backflow prevention devices for all threaded faucets around your home are available at major hardware or plumbing supply stores. Buy and install hose faucet vacuum breakers. They are available for approximately $5 to $10. Always keep hose ends out of contaminated water sources.

Contact Us
Backflow prevention assemblies for landscape irrigation systems are more expensive. These systems require a double check valve assembly at a minimum. Contact your landscape contractor, plumber, local plumbing store or the City of Everett Public Works Department for more details. For more information about cross-connection and backflow prevention contact the city's Public Works Department at 425-257-8800 or by email.