City water utility · Idaho

Backflow testing in Twin Falls, ID

City of Twin Falls Water Department's rules: who must test, when it's due, testers, filing and penalties.

Twin Falls requires a backflow device on lawn irrigation connected to city drinking water, and on other hazards such as fire sprinklers and boilers. Devices are tested every year by a certified tester. Pick one from the city's list. Call the Water Department to ask how to file the report.

At a glanceChecked Oct 18, 2026

Who

Lawn sprinkler systems: every year
Fire sprinkler lines: every year (some)
Homes (other than sprinklers): every year (some)

Due

Have your device tested every year.

Testers

City of Twin Falls Water Department's list (PDF, March 2026)

If late

The city's goal is 100% compliance.

Who must have a backflow test

Every irrigation system connected to Twin Falls drinking water, and not on pressurized irrigation, must have a backflow device. The city's survey also asks about fire sprinkler systems, boilers, hot tubs piped to the water supply, wells or ponds, and other equipment. Devices are tested every year. There is no grandfathering.

Lawn sprinkler systemsRequiredannual test
Applies to irrigation connected to city drinking water and not on pressurized irrigation.
Fire sprinkler linesSomeannual test
The city's survey asks whether you have a fire sprinkler system. Every connection that needs a backflow device must have one.
Homes (other than sprinklers)Someannual test
The city's survey also asks about boilers, hot tubs piped directly to the water supply, an alternate water source such as a well or pond, and other equipment connections such as soda machines and refrigeration.

Source: tfid.org · checked Oct 18, 2026

When the test is due

Have your device tested every year. Call the Water Department to ask when yours is due. If you have not told the city what is connected to your water, fill out its Backflow Assembly Survey and return it to the department.

Source: tfid.org · checked Oct 18, 2026

Finding a tester

Any certified backflow tester can test your device. Choose from the city's tester list, updated March 25, 2026, or hire any other certified tester. Many landscape companies have certified testers on staff. Call several testers and compare prices. The city does not vouch for a tester beyond testing backflow devices, so confirm the price before you book. You can check a license on the state's license search.

City of Twin Falls Water Department's tester list State tester lookup

PDF · dated Mar 25, 2026

Source: tfid.org · checked Oct 18, 2026

Filing the test report

Who files: Not published. Ask City of Twin Falls Water Department.
Fee: None listed by the utility
Form: Test report form

Testers use the city's backflow test report form. It records the hazard type (irrigation, boiler, fire system, domestic or beverage), the test kit serial number and its calibration date. Call the Water Department to ask where the completed report goes. State rules require your tester to send each report to you and to the water system within 15 business days of a passing test, or within 2 business days of a failed one.

Source: tfid.org · checked Oct 18, 2026

If the test is late or fails

The city's goal is 100% compliance. It keeps contacting owners until their devices are installed and tested. Call the Water Department to ask what happens if a test is late.

Failed test: State rules give 10 business days to repair, replace or isolate an assembly that fails its test. If that cannot be done in time, water service to it must be shut off.

Source: tfid.org · checked Oct 18, 2026

For testers working in Twin Falls

Certified backflow tester (Idaho Backflow Assembly Tester license)
City's Backflow Tester Certification / Questionnaire form
City's backflow test report form, with test kit serial number and calibration date

Fill out the city's online Backflow Tester Certification / Questionnaire. Call the Water Department with questions.

Tester registration Getting certified in Idaho

Source: tfid.org · checked Oct 18, 2026

The rules behind it

Twin Falls City Code (backflow devices required on irrigation systems connected to the city's drinking water): The city's backflow page summarizes the code requirement.
IDAPA 58.01.08.552.06 (Cross Connection Control Program, community water systems): State rule: annual tests by a licensed tester and 10 business days to fix a failed assembly.
IDAPA 07.02.04 (Plumbing Safety and Inspections): Linked by the city on its backflow page.

What Idaho requires statewide

Contact City of Twin Falls Water Department

Program: Backflow Prevention Program
Phone: 208-736-2275

Source: tfid.org · checked Oct 18, 2026

Backflow testing in Twin Falls: questions

Do I need a backflow test for my sprinkler system in Twin Falls?

Yes. City of Twin Falls Water Department requires backflow assemblies on lawn sprinkler systems to be tested annual test. Applies to irrigation connected to city drinking water and not on pressurized irrigation.

When is my backflow test due in Twin Falls?

Have your device tested every year. Call the Water Department to ask when yours is due. If you have not told the city what is connected to your water, fill out its Backflow Assembly Survey and return it to the department.

How do I find a backflow tester in Twin Falls?

Any certified backflow tester can test your device. Choose from the city's tester list, updated March 25, 2026, or hire any other certified tester. Many landscape companies have certified testers on staff. Call several testers and compare prices. The city does not vouch for a tester beyond testing backflow devices, so confirm the price before you book. You can check a license on the state's license search.

What happens if I skip my backflow test in Twin Falls?

The city's goal is 100% compliance. It keeps contacting owners until their devices are installed and tested. Call the Water Department to ask what happens if a test is late.

What if my backflow assembly fails the test?

State rules give 10 business days to repair, replace or isolate an assembly that fails its test. If that cannot be done in time, water service to it must be shut off.

Every fact on this page comes from City of Twin Falls Water Department's own pages, forms or code, checked Oct 18, 2026. Rules change: your notice and the utility have the final word. Spot a mistake? Tell us.