Short answer: Every lawn sprinkler connected to public water needs backflow protection, but most Centereach homes don't need a yearly backflow test. Suffolk County Water Authority (SCWA) says ordinary low-hazard homes get a dual check valve at the meter, while homes it rates high hazard, including irrigation systems that feed fertilizer or other chemicals, must install a reduced pressure zone (RPZ) device. RPZ and double check valve (DCV) devices have to be tested every year at your expense by a New York State certified tester who is, or works for, a Suffolk-licensed master plumber, and SCWA can schedule a shutoff if the test isn't done within its 60-day window.
What backflow is and why sprinklers matter
Backflow is water running the wrong way, from your property back into the public main. SCWA describes two ways it happens: back-pressure, when pressure in your home is higher than the street's, and back-siphonage, when pressure in the main drops, for example during a main break or heavy firefighting use. SCWA names garden hoses and irrigation systems as the most common sources of contamination, because sprinkler heads sit in soil that can carry fertilizer, pesticides and bacteria.
What SCWA requires at a home
SCWA's Cross Connection Control policy (booklet revised September 2025) makes backflow protection a condition of service, sized to the "degree of hazard" under New York's Sanitary Code, 10 NYCRR Section 5-1.31:
- Low or no hazard homes: a dual check valve installed at the water meter. That's the typical house with a plain sprinkler system.
- High hazard homes: an RPZ device. SCWA's examples include fire systems, chemicals in irrigation systems, a private well connected to the home and open-loop geothermal systems connected to SCWA water.
- Testing: RPZ and DCV devices must be tested every year at the customer's expense, with results submitted through SCWA's online test portal. If the test isn't done within the allotted 60 days, SCWA says the account "will be slated for shut off."
- Approved devices only: SCWA accepts only devices approved by the USC Foundation for Cross-Connection Control, installed downstream of the meter, and bills $25 for a failed installation inspection.
Not sure what you have? SCWA's Cross Connection Control Department (631-563-0266, weekdays 8 a.m. to 5 p.m.) can tell you whether your account has a testable device on file.
What the plumbing rules say about the sprinkler line itself
- New York State Department of Health policy (PWS 12): for a one- or two-family home on public water, the minimum protection for a lawn sprinkler is a vacuum breaker. A system that can create back-pressure from pumps or elevated piping, with no chemical injection, needs a double check valve assembly; a system set up for chemical injection needs an RPZ. Those assemblies are tested and maintained as the water supplier or health department requires.
- New York's Residential Code: the 2020 edition (section P2902.5.3), which most existing Long Island systems were installed under, calls for an atmospheric vacuum breaker, a pressure vacuum breaker assembly or an RPZ on the irrigation supply, no valves downstream of an atmospheric vacuum breaker, and an RPZ wherever chemicals are added. The 2025 New York codes have applied to permit applications since December 31, 2025, so ask your plumber which device the current code calls for on a new or rebuilt system.
Who can do the test in Suffolk County
Suffolk County Code Chapter 344, Article II, says a backflow tester must hold New York State certification and be a licensed master plumber or work for one, and must carry a County Consumer Affairs identification card for each master plumber who employs them. SCWA's test form (215B) has to be signed by the tester, the master plumber and the owner, with all certification and license numbers, or it comes back unprocessed. Before you hire anyone, check the master plumber's license (see how to check a plumber's license in Suffolk County); New York's Department of Health also publishes a list of certified backflow testers by county.
Simple steps for a typical Centereach home
- Put a hose bib vacuum breaker on every outdoor faucet. SCWA recommends these inexpensive screw-on devices so water only flows one way.
- Don't run fertilizer or chemicals through the sprinkler unless an RPZ is installed. SCWA treats chemicals in irrigation as high hazard.
- If you have an RPZ or DCV, book the yearly test with a certified tester working for a Suffolk master plumber, and make sure the result is entered in SCWA's portal.
- Adding or changing a sprinkler system? Have the plumber confirm the backflow device in writing, and handle the outdoor piping before the first freeze (see when to winterize outdoor faucets and pipes).
Sources
- Suffolk County Water Authority, Cross Connection Control booklet (rev. 9/9/25) (residential dual check vs RPZ, annual testing, 60-day shutoff, approved devices, $25 failed inspection)
- Suffolk County Water Authority, Backflow Prevention Devices (RPZ/DCV) and Cross Connection Control (back-pressure, back-siphonage, hoses and irrigation, hose bib vacuum breakers)
- Suffolk County Water Authority, Report on Test and Maintenance of Backflow Prevention Device (215B)
- New York State Department of Health, Technical Reference PWS 12 (residential lawn sprinkler policy) and certified backflow testers by county
- Suffolk County Code, Chapter 344, Article II, Backflow Testing
- New York State Residential Code 2020, Section P2902.5.3, Lawn Irrigation Systems; NYS Department of State, 2025 Uniform Code notice of adoption (effective Dec 31, 2025)
General information checked against SCWA, New York State and Suffolk County sources on Oct 30, 2026. Homes on a private well or a different water district (such as a village system) should check with that supplier.
Common questions
Do I need to get my sprinkler backflow tested every year in Suffolk County?
Only if you have a testable device such as an RPZ or a double check valve assembly. SCWA requires those to be tested yearly at the customer's expense, with results sent through its online portal. A typical low-hazard home has a dual check valve at the meter instead, which SCWA's policy doesn't list for annual testing.
When does a home need an RPZ on Long Island?
SCWA requires an RPZ at homes it rates high hazard, including irrigation systems that feed chemicals or fertilizer, fire systems, private wells connected to the home and open-loop geothermal systems connected to SCWA water.
What happens if I skip the backflow test?
SCWA's cross-connection policy says that if the annual test isn't done within the allotted 60 days, the account will be slated for water shutoff.
Who is allowed to test a backflow preventer in Suffolk County?
A New York State certified backflow tester who is a licensed master plumber or works for one, and who holds a Suffolk County Consumer Affairs identification card, under Suffolk County Code Chapter 344.
What's the cheapest way to protect my water at home?
SCWA recommends inexpensive hose bib vacuum breakers on every outdoor faucet so water can only flow one way, and keeping hoses out of pools, buckets and chemical sprayers.
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