A puddle under the backflow device by the meter is one of the most common calls in this topic. On an RP assembly, the funnel-shaped opening underneath is supposed to release water when the zone between the two check valves gets too close to supply pressure. It is a safety feature doing its job.
The question is why it is triggering. A steady drip, an intermittent spit and a full gush point to different causes, so note what you see, when it happens and whether sprinklers or other equipment were running at the time.
What the discharge pattern usually points to
| What you see | Likely cause | What it needs |
|---|---|---|
| Constant slow drip | First check valve not sealing, often debris or a worn disc | Test, clean or rebuild the check |
| Spits when flow stops or starts | Pressure swings in the supply or water hammer downstream | Test; ask about pressure fluctuations |
| Steady stream with no water use | Relief valve diaphragm or seat problem, or both checks fouled | Test and repair soon |
| Gushing water | Major internal failure or debris lodged in a valve | Close the upstream shutoff, then call a tester |
| Dripping only after work on the street | Sediment stirred up in the main | Often clears; test if it continues |
What you can safely do now
Watch it for a few minutes
Note whether discharge is steady or tied to water use, such as a sprinkler zone turning on or off.
Protect people and property
Keep the area from becoming a slip hazard and move anything the water could damage.
Shut off if it is gushing
Close the shutoff valve just upstream of the device, or the water main if needed. Water downstream will be off.
Photograph the tag
Brand, model, size and serial number let a tester bring the right repair kit.
Book a test
A tester can tell which valve is failing instead of guessing.
Quick facts about RP discharge
- Is some discharge normal?
- Brief spitting with pressure changes can happen; steady discharge is not normal
- Most common fix
- Cleaning or rebuilding the first check valve
- Retest needed?
- Yes, after any repair
- Hard water effect
- Scale and grit can keep a check from seating fully
Ask the tester
- Which valve caused the discharge: check one, check two or the relief valve?
- Was there debris, and could it come back?
- Is supply pressure fluctuating enough to trigger the relief valve?
- Does the repair include a retest and a filed report?
Common questions
Is a dripping RP wasting a lot of water?
A steady drip adds up over weeks, and a gushing relief valve can waste a large amount quickly. It is worth fixing promptly.
Can I just replace the relief valve myself?
Repairs to a testable assembly are normally followed by a test from a certified tester, and the supplier expects the report. Leave it to someone qualified.
Is the dripping water safe?
Treat it as non-potable. It comes from the zone between the checks, which is there to catch water that should not go back to the supply.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.