New Hampshire: State rules

New Hampshire RSA 485:11 says there shall be a backflow prevention device at every connection to a public water system if the facility may pose a hazard to water quality, as determined by the Department of Environmental Services. The facility receiving the water is responsible for having the device installed, serviced, and tested by individuals qualified by license or certification. Testing occurs twice annually unless the supplier determines the facility is a low hazard, in which case testing is annual. High-hazard devices are tested twice annually. A residential property with only a non-testable device is not a hazard facility and does not require annual testing. Irrigation, a private well connection, or another feature may still make a residence high hazard.

Checked against official sources on October 11, 2026. Rules and links change; confirm with the office listed before you act.

The same section limits certain distribution-side work, including inspection and testing of backflow preventers directly adjacent to and required for protection of the drinking-water distribution system, to qualified individuals. Testing after installation or repair is required so new and repaired devices work properly. DES’s model cross-connection program says a certified inspector must be certified through the New England Water Works Association Certified Backflow Prevention Device Inspectors/Testers Program. The model says periodic inspections and tests are performed by that NEWWA-certified inspector at the owner’s expense. High-hazard devices in the model are inspected and tested at least semiannually, and low-hazard devices annually.

The model defines an approved device as one manufactured to allow accurate testing and inspection and tested and approved by the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research. DES posts training notices for the NEWWA course, which includes written and practical exams for the NEWWA inspector/tester certification. DES also publishes a fact sheet, DWGB-11-3, listing backflow prevention device testing companies. That fact sheet is a company list, not a statement that DES itself issues the tester card. The statute places qualification in “license or certification,” and the model program specifies NEWWA.

A customer should ask whether the supplier has classified the facility as high or low hazard, because that choice changes the test from twice a year to once a year. A residence with a non-testable device and no irrigation or private well connection is treated differently from a commercial service. No statewide fee is printed in the statute section used here. The model says the owner pays for the inspection and test.

Official resources in New Hampshire

RSA 485:11

Sets twice-annual testing, the low-hazard annual alternative, and the residential non-testable exclusion.

DES model cross-connection program

Says inspectors are certified through the NEWWA backflow inspector/tester program.

DES testing-company fact sheet

Department document listing backflow prevention device testing companies.

Key facts for New Hampshire

The customer facility is responsible for installation, service, and testing by individuals qualified by license or certification.
Testing is twice annually unless the supplier determines the facility is low hazard, in which case it is annual.
A residential property containing only a non-testable device is not a hazard facility and does not require annual testing.
Irrigation, a private well connection, or another hazardous feature may make a residence high hazard.
The DES model program requires NEWWA Certified Backflow Prevention Device Inspector/Tester certification.
The model says approved devices are tested and approved by the USC Foundation.

What to do next

Ask the supplier whether your facility is high hazard or low hazard before you assume the test frequency.
Ask for the NEWWA inspector/tester certification the model program names.
A house with only a non-testable device is not automatically on an annual test schedule.
If you have irrigation or a private well tied to the plumbing, tell the supplier; the statute flags those features.

Looking for your city or county in New Hampshire?

We haven't found official program-level pages for New Hampshire we can verify yet, so we don't show local numbers here rather than guess. Here's what to use instead, in order:

General Start with the statewide information above. It applies across New Hampshire, but cities and counties can add their own steps, fees or deadlines.
Call to confirm Ask the official office. They have the current local rule, fee and form.
New Hampshire DES backflow device requirements
Website →
Phone not shown: use the contact page on the official website above.
Your city or county office: Local governments →
Not sure who handles it locally? USAGov's free help line, 1-844-872-4681, or the New Hampshire page on USA.gov can point you to the right office.
Know the current info? Tell us and include a link to the official page. We check every tip before it goes up.

Helpful guides

Backflow tester planner →

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