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Backflow Testing Guide

The following guides provide information regarding irrigation systems and backflow prevention devices. All irrigation systems must obtain a permit prior to installation and all backflow preventers must be inspected annually by June 1. For a complete listing of certified backflow testers, please visit the state of Missouri Department of Natural Resource website.

All lawn irrigation systems, fire sprinkler systems and commercial service lines are required to contain a backflow prevention device and be tested annually by a state of Missouri-certified tester. Annual backflow test reports are due by June 1. The City of Wentzville has implemented a fee structure pertaining to backflow reporting. The fee structure is as follows:

Water Backflow Filing FeeReceived DateFee
Early BirdPrior to June 1$10
StandardJune 5 through July 1$15
Late FilingAfter July 5$30

Please be aware that the test date will not override the date of receipt at our office. Each report is stamped on the date it is received by our office. This received date will determine the fee that your customer will be charged on their water account with the City of Wentzville.

There are three options for submitting your test results:

Email (Recommended)

Email backflow report to
Only one PDF per email will be accepted. You are welcome to scan multiple reports into ONE PDF, but please do not attach more than one PDF per email.


Deliver backflow report in person to the City of Wentzville


Mail backflow report to:
City of Wentzville
Attn: Backflow Reporting
1001 Schroeder Creek Blvd.
Wentzville, MO 63385

All reports submitted by email will receive an emailed confirmation receipt. Receipt of reports can be confirmed by the City of Wentzville by calling (636) 639-2165.

In lieu of testing, lawn irrigation systems may be deactivated by removing their backflow device. Please schedule a deactivation inspection by the City’s Water Division before June 1.