What backflow is and why Raleigh cares
Raleigh Water defines backflow as the undesirable flow reversal of water, liquids, gases or other substances into its public water supply. It can happen when pressure in the distribution system drops relative to a service line, for example during firefighting, a water main break, high usage, or backpressure from a pump. A backflow assembly lets water travel in only one direction and, when it works, stops contaminants such as pesticides, fertilizers or animal waste from entering drinking water.
Every connection to Raleigh Water's system must have some type of containment backflow protection, according to the city, and there is no grandfather clause. For most residential customers, approved protection is the dual check device in the meter box. The city cites the Safe Drinking Water Act Amendments of 1996, NC DEQ, the NC Plumbing Code and Raleigh City Code as the basis.
Irrigation systems need a reduced pressure assembly
Raleigh Water says a reduced pressure assembly, or RPZ, is required for residential lawn irrigation systems, and also when a resident uses public domestic service while having a private irrigation well on the property. The containment assembly is the first backflow assembly after the water or irrigation meter, with no unprotected taps before it.
The city describes a simple check: slowly close the shutoff valve to the backflow assembly, then try faucets, irrigation and toilets. If water still flows to fixtures, you do not have proper backflow protection; if it stops, you are properly contained. If your irrigation also drains through pipes that freeze, see frozen pipe prevention.
The testing schedule
Raleigh Water says a residential irrigation backflow assembly must have a passing operational test submitted by July 1 every three years. Commercial irrigation assemblies must be tested annually by July 1, and other assemblies annually according to the property's ZIP code. Customers with a testable assembly receive an initial testing notice two months before the due date.
Compliance means the assembly was tested by a City of Raleigh Certified Tester and the passing report was submitted to Raleigh Water's vendor, VEPO. The city explains why testing is required: a backflow assembly is a mechanical device subject to failure, and it is impossible to tell whether it works by appearance; an operational test with a differential gauge is needed.
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The city does not provide testing; it maintains a list of certified testers, who must hold a certification from a locally approved school and keep test kits calibrated annually. Under Raleigh City Code 8-2154, the consumer is the responsible party to maintain and test the assembly, so the homeowner pays.
For installation, repair or replacement, Raleigh lists who is allowed: licensed Class I plumbers for all structures, licensed Class II plumbers for single-family dwellings only, licensed utility contractors within five feet of the building, and Restricted Limited Plumbing contractors for exterior assemblies on service piping two inches or smaller. Our license guide explains those classes.
Failed tests and new assemblies
If an assembly fails, Raleigh says it must be cleaned, repaired or replaced, and a successful re-test must be submitted to the Cross Connection Control Program within 15 days. Newly installed assemblies need an operational test too, because parts can deteriorate before installation.
A failed or leaking assembly can also waste water; see leak detection. Irrigation meters are billed at the Tier 3 rate under Raleigh Water's rules, so leaks there cost more per CCF; our high bill guide explains the tiers.