Backflow device types
RPZ assembly
Used on higher-hazard connections — two check valves plus a relief valve that discharges if they aren’t holding.
Double check valve assembly
Two independent check valves for lower-hazard connections — no relief valve, doesn’t vent externally.
Cross connection
Any point where potable water could connect to a contamination source — irrigation, chemical feed, non-potable storage.
Who needs a test in Jamestown?
Confirm the boundary
Jamestown BPU identifies which connections require a device and sets testing expectations.
Check requirements by scope
An RPZ and a double check assembly aren’t interchangeable — confirm the correct type for your connection.
Use address-specific facts
An irrigation system added years later can create a requirement a neighboring property doesn’t have.
What happens during an annual test
Confirm symptoms & system
Device type, location, and any reported symptoms like a dripping relief valve or a failed prior test.
Inspect & test on site
Test cocks and gauges confirm each check valve, and the relief valve where applicable, hold within tolerance.
Explain findings & next steps
Pass, fail, or pass with a noted repair — plus the documentation needed for the property record.
If the device fails a test
A failed test doesn’t necessarily mean full replacement — many failures involve a single worn seal, stuck check valve, or debris. A continuously dripping RPZ relief valve is a common early sign of a check valve no longer sealing. Because this is a pressurized system, avoid disassembling it yourself.
Installation, repair & reporting
A new device is typically required when a property adds an irrigation system, fire suppression line, or a commercial connection the utility identifies as a cross-connection risk — the correct type depends on hazard level, and choosing wrong can create a compliance gap even if the device functions. Repair addresses individual components like seals or a relief valve without replacing the whole assembly. Reporting documents the completed test or repair result for the utility, which keeps compliance records for each connection.
Backflow preventer versus sewer backwater valve
A backflow preventer stops potable water from flowing backward into the drinking supply. A backwater valve stops sewage from a surcharged sewer line from flowing back into your building. See backwater valve installation for that separate topic.
Scheduling & test documentation
Before the appointment, have the property address, device location, prior test notice, and any previous report available. We identify the assembly, review the reason for testing, perform the applicable checks, and explain the result. When documentation is required, the report identifies the property, device, test result, repairs performed, and next step — keep a copy with the building’s maintenance records, especially for commercial, rental, irrigation, boiler, or fire-line connections.
Backflow testing FAQs
How often is a backflow device tested?
Generally annually — confirm your device’s specific schedule with the Jamestown BPU.
What information is included in the test record?
Property, assembly type, measured results, repairs if any, and the final outcome.
What happens if it fails?
At least one component isn’t holding tolerance — repair or replacement is needed before it can pass.
Why is an RPZ relief valve dripping?
Usually means a check valve is no longer sealing correctly.
Does every home need a backflow preventer?
No — depends on the type of connection, such as irrigation or a fire line.
Is a backwater valve the same thing?
No — they protect against opposite problems. See backwater valve installation.
Backflow test due or device failed?
We’ll help you sort out the next step.