What is backflow testing?

South Carolina requires every public water system to run a cross-connection control program. The SCDES Cross Connection Control page says the program protects drinking water by identifying and eliminating cross connections, and that testing of backflow prevention assemblies is done by a state-certified tester. Assemblies used in South Carolina have to be on SCDES’s list of approved backflow prevention assemblies. The filename on the state site spells “equipment” the way the URL shows.

What backflow is

Greenville Water’s backflow page defines backflow as the unwanted reverse flow of water or other substances in a plumbing system, which can contaminate potable water. That page says every connection can let non-potable water into the public system, which is why customers whose water presents a hazard must install a device or assembly and have it tested annually under SCDES and Greenville Water standards.

That sentence is Greenville Water’s. The duty to control cross connections is statewide. R.61-58.7(F) says no person may install or keep a cross connection between a public water system and any other non-public water system, a sewer, or a line from a container of liquids or other substances, unless an approved backflow prevention device or assembly sits between the public system and the source of contamination.

What the annual test covers

Section (7) of that rule applies when a double check valve assembly, a pressure vacuum breaker, or a reduced pressure principle assembly is installed to protect the public system from a customer’s service:

• A certified tester tests the assembly after installation and before the customer uses it.
• Except for the low-hazard residential irrigation case below, a certified tester tests each assembly at least once a year.
• The public water system receives a written report of the inspection and testing results. The certified tester who made the test submits that report.
• After a repair of any kind, the assembly is tested again immediately.

This page does not list gauge readings or pass/fail numbers. Those belong on the tester’s report and on the form your utility uses. SCDES publishes a sample backflow device test report.

Low-hazard lawn irrigation is a different case

Section (3) says a public water system with low-hazard residential irrigation connected to it must have a written policy. The minimum device the regulation names for that case is a residential dual check. If the utility’s policy requires a testable assembly instead, the policy sets how often that assembly is tested. If the policy uses dual checks, it sets how often those devices are changed out. Records have to show the system is following its own schedule.

A residential irrigation system that adds chemicals, or that is also connected to a water source other than an approved public system, is a high hazard under that section. Section (4) then calls for an air gap or an approved reduced pressure principle assembly. If your notice does not say which case you are in, use the notice. This site does not guess.

Who may do the test

In R.61-58, a certified tester is a person holding an up-to-date backflow prevention assembly tester card issued by the Department. The classification that tests assemblies for the general public is the General Tester. A Limited Tester tests only assemblies the employer owns. How those cards differ, and how SCDES issues them, is on General vs Limited.

What the test is not

A test is not a price. The cost guide keeps a third-party range labeled as a range, separate from any utility fee. Greenville Water says it does not install or test backflow preventers. On that system the customer hires a certified tester, and the tester files the result.

Other utilities publish their own notice steps. Spartanburg Water’s are summarized on the Spartanburg Water page. If your water system is not one of those, the deadline and the filing method on your letter control.

Finding a tester in the Upstate

County pages copy General Testers from the SCDES report printed July 9, 2026. Start with Greenville County, or open the county on the tester’s address: Spartanburg, Anderson, Pickens, Oconee, Laurens, Cherokee. Confirm the tester’s current SCDES card before you hire. A row here is not an appointment.

Official links are collected on Resources.

Sources read for this page on October 6, 2026: the SCDES program page, R.61-58 on des.sc.gov, the SCDES sample test form, the January 2026 approved-assembly list, and Greenville Water’s backflow prevention page.