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Joliet Backflow Device Survey

Post Date:08/27/2019

The City of Joliet is conducting a survey to identify properties with a backflow device or reduced pressure zone (RPZ) valve. A backflow device is installed onto your plumbing system to protect your drinking water and the City water supply from contaminants. RPZ valves are required when a building is equipped with an:

Irrigation system, contaminants can enter your system from fertilizer or pesticides that are sprayed onto lawns

  • Large boiler or fire suppression system, where water is stagnant or trapped

Certain things (water main break, leak, hydrant flushing or use) can cause the stagnant or contaminated water to back-up into the public drinking water supply. An RPZ Valve will prevent this from occurring.  For these reasons, Illinois State Law requires the use of an RPZ as outlined in the Illinois State Plumbing Code. The law not only requires the use of an RPZ device, but the device must also be tested every year by a licensed plumber with a Cross Connection Certification License. Once the RPZ is tested, the certification paperwork is forwarded by the plumber to the City.

Notice of the survey will be sent out to every resident and business owner, as an insert in their water bill.  We are asking that residents go online to complete the survey at The survey is available in both English and Spanish. The water bill insert, with a link to the survey is also available on the City’s website at  It is important that water customers do their part to protect the City’s water supply from cross-contamination.