Protect Your Drinking Water

ERMU is dedicated to providing and maintaining safe, healthy drinking water. Backflow prevention is essential to keeping our water safe, and it is everyone’s responsibility. 

What is backflow?

Backflow is the reversal of flow of non-potable water, contaminants, and/or other substances into the treated drinking water system. Backflow could impact the quality of the water at homes, businesses, and other facilities with the potential to create health hazards when the water is used for drinking, cooking, or bathing. Although these undesirable occurrences are rare, the effects on the community’s health and safety can be significant.

Most homes and businesses utilize backflow prevention devices to limit the risk of contaminating the community water supply. Some customers are required to install and maintain these devices on the main water service lines.

A loss of pressure within a plumbing system that has no backflow prevention device may allow water to be drawn back into the system and contaminate it. Consumption of the contaminated water could result in severe illness. In addition, once a plumbing system is contaminated, any contamination can be drawn into the community water supply and compromise the water for many others.

What is cross connection?

Cross connection refers to any connection between a potable (drinkable) water supply and non-potable sources, including liquids, solids, or gases that could contaminate drinking water. Irrigation systems present a risk of contamination from stagnant water, lawn chemicals, or fertilizers.


What is a backflow prevention assembly?

The mechanism designed to prevent backflow is known as a backflow prevention assembly. The most common of these devices installed on irrigation systems include:

  • Pressure Vacuum Breaker (PVB) devices
  • Reduced Pressure Zone (RPZ) devices

Backflow prevention devices are required on irrigation systems, and you may notice them alongside your house. The device protects you by preventing water that’s been released into your irrigation system from being drawn back into the home, avoiding potential consumption in the case of a loss of system pressure.

Testing Process

The testing of backflow prevention assemblies helps to eliminate possible contamination of the public water distribution system.

State of Minnesota Plumbing Code 4714.603.523 requires that all backflow prevention devices be tested upon installation and annually thereafter by a certified backflow assembly tester and rebuilt as needed. Please note, this certification goes beyond what a plumbing license includes. We have partnered with HydroCorp to help manage our backflow prevention program. Please submit test results electronically to HydroCorp.

Please contact HydroCorp at 844-HYDROINFO (493-7646) with any questions regarding cross connections and backflow prevention.

Backflow prevention device