Local Law · Systems
Backflow prevention device testing
Buildings with DEP-mandated backflow preventers must test each device annually to protect the public water supply, with a plan on file and results submitted to DEP.
What backflow prevention requires
Many buildings — especially those with boilers, cooling systems, irrigation, or commercial uses — are required by the Department of Environmental Protection to install backflow prevention devices that stop contaminated water from flowing back into the public supply. Each device must be tested annually by a certified backflow tester, with an approved plan on file and results submitted to DEP.
How to comply
- Confirm whether your building has DEP-mandated backflow devices and an approved plan.
- Have each device tested annually by a certified tester.
- Submit results to DEP and correct any failures.
Reviewed against current NYC agency guidance by the NYC Building Compliance editorial team. Found something out of date? Tell us. Informational only — not legal or engineering advice.
Frequently asked questions
Which buildings need backflow prevention testing?
Buildings with DEP-mandated backflow prevention devices — common with boilers, cooling systems, irrigation, or commercial use.
How often must backflow devices be tested?
Annually, by a certified backflow prevention device tester, with results submitted to DEP.
Who enforces backflow requirements?
The NYC Department of Environmental Protection (DEP).
Need help handling this?
Tell us about your building and we’ll connect you with a certified backflow tester who works on NYC compliance — no cost to ask.
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