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If you received a letter from the City of Tumwater Public Works Department about installing backflow prevention devices, please contact Public Works Operations & Maintenance at (360) 754-4150.

Cross-Connections may risk contaminating drinking water

Throughout the U.S., there are many cases of drinking water becoming contaminated as a result of cross-connections.  A cross-connection is a connection between the potable drinking water system and a non-potable substance. This interconnection becomes a hazard when backflow conditions caused by a water main break, fire, pump failures, or increased demand result in pressure losses and contaminants flowing into the city’s drinking water system.

What is Backflow?

Backflow occurs when the pressure in the drinking water system drops, siphoning water and any substances in it into the public water system.  This is called backsiphonage and may occur when there is an unusually high use of water in an area, such as firefighting or a broken water main.  Backsiphonage may also occur when a hose is left in a full mop bucket, or in a watering can containing garden chemicals.

Another type of backflow, called backpressure, occurs when there is a cross-connection with a container or pipe containing non-potable substances under pressure.  When the public water system’s pressure drops, the pressurized system actually pumps the material into the public system.

A story about contamination from Cross-Connections...

In 1993, an Oregon homeowner installed an irrigation system using water pumped from a decorative pond in an area near an old septic drain field.  When the pond’s pump failed, the homeowner connected a hose from the home’s drinking water system to the irrigation piping.  When the pump was brought back online, it forced pond water through the hose connection, through the home, and into the city’s potable water system.

In 1982, a Michigan resident was spraying his garden with pesticides using a common hose and sprayer attachment. While he was applying the pesticide, the public water system needed to shut down temporarily. The homeowner noticed a drop in pressure and within a few moments, the pesticide disappeared from the container: Backsiphonage had drawn the pesticide into the hose, through the house plumbing, and into the public drinking water system. 

Backflow prevention

The City of Tumwater is committed to ensuring your drinking water remains clean and safe.  The Washington State Department of Health requires proper backflow prevention assemblies on all commercial properties and some residential properties that are connected to the City’s water system.

What can you do?

  1. If a hazard exists on your property, you must install a backflow prevention device in a manner accessible to both a certified tester and the City’s inspector.
  2. If you have a backflow prevention device installed, you must have it inspected and tested annually and you are required to submit the results of your test to the City.
  3. It is the property owner’s responsibility to maintain the device, including providing freeze protection.  For guidance on maintaining your device, refer to the manufacturer’s guidelines.
  4. Our staff can help you determine if you have cross-connection risks. Complete theCross-Connection Control Survey online and our staff will contact you.