Commercial Toilet Keeps Running? How to Troubleshoot a Flushometer
If a manual commercial flushometer will not shut off, close the control stop first. Common causes include a blocked metering bypass, debris under the diaphragm, damaged internal parts, the wrong repair kit, or inadequate supply pressure.
Last reviewed 2026-09-12 · General facility-maintenance information, not a substitute for site procedures, manufacturer instructions, codes, or qualified professional judgment.
Quick answer
Safety boundary
Symptom → cause → first move
Continuous full flow
Check: Blocked bypass, debris, damaged relief assembly
First move: Shut off water; inspect and clean internals.
Flush lasts too long
Check: Restricted bypass or wrong-volume parts
First move: Verify kit and metering path.
Weak flush
Check: Stop too closed, wrong kit, poor supply
First move: Adjust stop gradually; compare nearby fixtures.
Handle leaks/sticks
Check: Worn handle assembly
First move: Use correct handle repair kit.
What to check first
Bring these
- Flat-blade screwdriver
- Smooth-jaw adjustable wrench
- Rags or towel
- Correct diaphragm/inside-parts kit
Before touching anything
- Confirm the exact location and complaint.
- Photograph labels, settings, and error codes before changing anything.
- Know how to isolate water, power, or the affected area if needed.
- Follow site-specific PPE, lockout/tagout, ladder, roof, and access procedures.
Step-by-step procedure
- 1Identify the valveRecord manufacturer, series, toilet/urinal type, and flush volume before ordering parts.
- 2Close the control stopTurn clockwise gently; do not force a seized stop.
- 3Relieve pressure and open the topOperate the handle once, catch residual water, and remove the top cover carefully.
- 4Inspect the diaphragm assemblyLook for grit, scale, torn rubber, distorted plastic, and debris on sealing surfaces.
- 5Clean the metering pathRinse serviceable parts. Never enlarge the small bypass opening.
- 6Install the correct kitMatch manufacturer, fixture type, and flush volume; seat parts naturally.
- 7Restore water and testOpen the stop slowly, check for leaks, and test several flushes.
Stop and call a licensed professional when
- Control stop will not shut off or is leaking
- Valve body or supply piping is cracked/corroded
- You cannot positively identify the correct parts
- Several fixtures suddenly have pressure problems
- Correct internal service does not stop the run-on
Common mistakes
- Buying a kit because it looks similar
- Using toothed pliers on chrome
- Forcing a stuck control stop
- Poking the bypass with wire or a drill bit
- Opening the control stop fully by default
FAQ
Why does a clogged bypass make it run?
The bypass meters water into the upper pressure chamber so the diaphragm can close on time.
Are toilet and urinal kits interchangeable?
Do not assume so; flush volumes and metering parts can differ.
Should the control stop be fully open?
No. Open only enough for reliable fixture performance.
Can I use a paper clip to clear the bypass?
No. Use the manufacturer-approved cleaning method without enlarging the opening.
Parts for this repair
Sloan flushometer rebuild kit
Repair kit for compatible Sloan flushometers; verify model and GPF.
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