CSLB C-36 Plumbing ContractorService, Repair, and MaintenanceMedium
A tenant reports that their toilet continuously runs, even after flushing, but the water level in the bowl is normal. You observe the fill valve is constantly trickling water. What is the most likely component failure?
- AA worn-out flapper valve that is not sealing properly.
- BA cracked toilet bowl, allowing water to escape.
- CA faulty fill valve assembly that is not shutting off.
- DAn incorrectly adjusted float cup, set too high.
Show answer & explanationAnswer & explanation
Correct answer: C. A faulty fill valve assembly that is not shutting off.
If the fill valve is constantly trickling water, it means the mechanism that tells the valve to shut off once the tank is full is not working correctly. This is a direct failure of the fill valve assembly itself, which includes the float and the valve's internal components, preventing it from stopping the water flow into the tank.
Why the other options are wrong
- A. A worn-out flapper would cause water to slowly leak from the tank into the bowl, leading to the fill valve turning on intermittently to refill the tank, but not a constant trickle from the fill valve itself.
- B. A cracked toilet bowl would cause water to leak onto the floor, not cause the fill valve to continuously run into the tank.
- D. An incorrectly adjusted float cup (set too high) would cause the tank to overfill and water to run into the overflow tube, which would then trigger the fill valve to run continuously, but the *root cause* of the continuous trickle *from the valve* is its inability to shut off, often due to an internal defect or the float mechanism not signaling correctly.
Toilet Fill Valve Failure
When the fill valve in a toilet tank continuously allows water to flow, even after the tank is full.
- Prevents the toilet from conserving water.
- Often indicated by a constant trickling sound.
- Caused by worn internal components or a malfunctioning float mechanism.
- Requires replacement of the fill valve assembly.
Memory trick: The fill valve sighs, 'I can't close my eyes!'