Skip to main content


Backflow is the reverse flow of water through pipes and hoses. This reverse flow poses a risk of water contamination to public and domestic drinking water systems. For more information please contact the Backflow Team at 208-888-5242.

Information for Residents

  • Back Pressure: Back pressure occurs when the pressure in a pipe or hose is greater than the incoming pressure. Connection to a booster pump or private well. 
  • Back Siphonage: Back Siphonage occurs when there is negative pressure drawing contaminants into the water supply.
  • Cross Connections (Dual Connections): Cross connections occur when two separate water systems are connected together mixing different sources of water (i.e. pressurized irrigation water lines connected to your home's drinking water lines). Through these connections, it is possible to introduce non-potable, used, unclean, contaminated water or other substances into the potable water supply.

  • Back Pressure and Back Siphonage require the installation of an approved backflow assembly to be installed. These assemblies need to be tested annually by a certified backflow assembly tester and the results submitted to the City Water Division. 
    • Three common types of backflow assemblies can be found here»
  • Cross Connections (Dual Connections) ARE NOT ALLOWED within the City of Meridian for residential use and must be removed if currently installed. View or download the dual connection removal requirements PDF below.

To find out if you require a backflow assembly, review the process below. 

Do you need your backflow assembly tested quiz

If you need to install a Backflow assembly, a permit is required.  To apply for a permit, visit

As of May 1st, 2018, Double-Check Assemblies are no longer allowed in lawn sprinkler applications.

All backflow requirements will be enforced by the Idaho State Plumbing Code (ISPC). 

Any double-check backflow assemblies installed prior to the code change will not need to be removed unless they can no longer be repaired. At that time, they will need to be upgraded with a Reduced Pressure Backflow Prevention Assembly (RPBA) or a Pressure Vacuum Breaker Assembly (PVB).

Learn More About Backflow

Backflow Compliance

Per Meridian City Code, Backflow Prevention Assemblies must be tested annually by an Idaho Licensed Backflow Tester. Passing test reports must be submitted to the Meridian Water Division on or before their due date to avoid water service interruption.

Was your backflow assembly tested by the annual due date?

  • Yes

Contact your tester and have them submit the test report or, if you have a copy, you can email it to Once the passing test report is received, water will be restored on the same business day.

  • No

Contact an Idaho-licensed backflow tester and schedule a test to be performed within 10 business days. See the link below for a list of local backflow testers.


      • The City of Meridian Cross Connection Division must receive confirmation of the scheduled testing date from the tester only to have the water service restored.
      • If the test report is not received by the scheduled date, the water service will once again be subject to disconnection. Water service shall not be restored without a passing test.

When a backflow prevention assembly fails to pass, the Backflow Assembly Tester must submit a failing test report to the Meridian Water Division within two (2) business days.

After repairs and retesting have been completed, a passing test report must be received by the Meridian Water Division within ten (10) business days of the failure date to avoid water service interruption.

The City of Meridian has created a courtesy list of local testers who have volunteered their contact information and pricing. 

Backflow Tester List »


Backflow Testers

© Copyright 2024, Meridian, Idaho. All rights reserved. Privacy Statement Terms of Use Accessibility