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RPZ Testing Information

Illinois Environmental Protection Agency (IEPA) annual testing of RPZ (Reduced Pressure Zone) Backflow Preventers

An RPZ backflow preventer is required by the IEPA and protects your domestic water supply and the Village's water distribution system from potential contamination. When the pressure drops in the Village's water distribution system it is possible to have the water in your domestic plumbing drawn back into the Village's water distribution system. The RPZ backflow preventer prohibits any sprinkler water from going back into the Village's water distribution system or your domestic supply. This is especially important since some people use chemicals (fertilizers, insecticides, etc.) on their lawn that could contaminate the Village's distribution system as well as your domestic supply.

IEPA regulations require that all RPZ backflow preventers connected to any public water system be tested annually. The IEPA requires that the implementation, execution, and monitoring of these testing stipulations are the responsibility of the local authority managing the public water supply.

If your RPZ is part of your sprinkler system and it was disconnected and drained out for the winter, the most appropriate time to have your RPZ tested is in the spring while starting up your system. To meet the IEPA requirements, all domestic supplies with an RPZ backflow preventer must be tested and certified by a State licensed plumber. The Mokena Water Department asks that all backflow preventers be tested before June 1st. Failure to do so could result in the disconnection of your water service.

To have your RPZ tested, you may contact the company that installed the sprinkler system. However, any licensed plumber with IEPA certification to test backflow preventers may perform the test. The Water Department recently surveyed some local plumbers for their testing prices. Please check our website for the List of Plumbers. Once the inspection has been completed, your plumber must tag the RPZ with the test date, results, and a log of any required maintenance. After testing, please make sure the plumber sends a copy of the test results to the Village of Mokena’s Water Department. It may be mailed to the Water Department at 11400 W. 191st St., faxed to (708) 478-0236 or emailed to

2020 RPZ Testing Plumber List










A&D Plumbing, Inc.



(815) 726-1004






Carefree Lawn Sprinklers



(815) 462-3300



$55 w/ system

$80 otherwise



J.E.M. Plumbing



(708) 478-3833






Krupske Sprinkler Systems, Inc.



(815) 464-6801






Provancal Brothers, Inc.



(708) 389-3710






Werner Nugent Plumbing, Inc.



(708) 385-5250








    Village of Mokena | 11004 Carpenter Street Mokena, IL 60448
    Phone: (708) 479-3900  |  Fax: (708) 479-4844
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