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  • Backflow Prevention

Your Water

  • Water Sources
  • Water Distribution System
  • Long Term Water Supplies
  • Drinking Water Quality
  • Backflow Prevention
  • Hydrant Flushing
  • Capital Improvement Projects
  • Water Supply Shortage Plan

Backflow Prevention

Protecting And Eliminating Cross Connections

What Is Backflow? 

Double Check Valve Assembly Backflow DeviceDrinking water flows from the source to your tap in pressurized water pipes. Normally it flows in one direction, although under certain circumstances it can flow in the opposite direction, or “backflow.” When backflow occurs, water runs backwards through the water system. The water flowing backwards could contain something that might contaminate the drinking water supply. TVWD strives to maintain positive pressure in the system at all times, but events such as main breaks and fire fighting can contribute to backflow conditions.

What Is A Cross Connection?

A cross connection is any connection between piping that carries drinking water (also known as potable water) and the piping or fixtures that carry other types of water or substances that are not safe to drink or may impact the taste or odor of water (also known as non-potable water). Common cross connections include hot tubs, sprinkler and irrigation systems and auxiliary water systems (wells).

Why Does TVWD Have A Backflow/Cross Connections Department?

TVWD's Cross Connection Program seeks to eliminate or protect all cross connections in the public water system and help customers comply with backflow prevention practices and regulations. All cross connections must be inspected once a year by a certified backflow tester (PDF) to ensure proper operation. If you have a cross connection that is required to be tested, you will receive a letter from TVWD with guidance about how to get this done.

If you are unsure if you water using fixtures needs a backflow assembly or an annual backflow test, contact your plumber, landscaper or TVWD's Cross Connections Department.

More Cross Connections Resources:

  • TVWD Certified Backflow Testers (PDF) 
  • TVWD Backflow Brochure (PDF)
  • Irrigation and Sprinkler Safety Brochure (PDF)
  • Cross Connections/Backflow Assembly Standards (PDF) - contains diagrams on how backflow devices are used
  • Standard Details (PDF - 3.7 MB) - contains backflow device specifications
  • Standard Details (Autocad - Zipped file, 6.2 MB)
  • E-mail request for Standard Details
  • Oregon Department of Human Services Backflow Prevention Web Site
  • American Backflow Prevention Web Site

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