What is backflow?
Backflow is the backward flow of water through a pipe. The normal direction of water flow is from the utility water main into homes or businesses. The backflow of water from home plumbing systems into the community drinking water supply happens when water is pulled backward due to a pressure loss in the utility main pipe or pushed back by a pressure source like a well pump.
  • Back siphonage creates a vacuum as water drains toward the community water system. Water or fluid can be siphoned or pulled into the utility main water line (e.g., a garden hose with one end immersed in a pail of soapy water or a hose immersed in a swimming pool).
  • Back pressure can develop when irrigation well pumps are connected to drinking water for pump priming or blending drinking water with well water to reduce a “rotten egg” odor or driveway staining.

Show All Answers

1. What is a cross connection?
2. What is backflow?
3. Why are backflow preventers needed?
4. Who needs a backflow preventer?
5. What is a backflow prevention program?
6. How can this contamination happen?
7. What is an indirect cross connection?
8. Why does this backflow preventer need to be installed in front of my house?
9. Can I cover or hide the backflow preventer?
10. Why do some backflow preventers need to be tested every year?
11. My backflow preventer sometimes leaks water from a relief valve. Can I remove or plug the valve to prevent water loss?