Backflow testing for sprinkler systems in O'Fallon, MO
Missouri · Last checked November 2026
O'Fallon, Missouri requires annual backflow tests on irrigation systems, with reports due June 1. Residential addresses that file late pay a $30 late fee.
Key facts
- Deadline
- June 1.
- Late fee
- $30 for residential addresses.
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How it works
A lawn sprinkler system connects to drinking water, so it needs a backflow preventer to stop fertilizer and lawn water from being pulled back into the pipes. Most cities require that device to be tested by a certified tester, usually every spring, with the report filed by a set date. Miss it and you can face late fees or a water shutoff notice.
- Find the backflow device near where the sprinkler line leaves the house, often a valve assembly above ground.
- Check your city's deadline. Many fall between May 31 and June 15.
- Hire a tester certified in your state, or wait for the utility if it tests for you.
- Make sure the tester files the report with the city, and keep a copy.
- Not using the sprinklers? Ask about an inactive or deactivation certificate instead of a test.
What it costs
A residential backflow test usually costs about $50 to $150. Some cities add a small filing fee, around $12, and late fees can run $30 to about $80. Repairs to a failed device cost more.
Other O'Fallon home rules
More in Missouri and nearby
- Wentzville Test every year
- Apex Test every 2 to 3 years
- Cary Utility runs the test
- Bel Aire Test every 2 to 3 years
- South Holland Test every year
- Geneva Test every year
Sources
Last checked November 2026. Programs open, close and change funding every year. Confirm with the city before you hire anyone. Report a change.
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