Commercial toilet keeps flushing / won't shut off (Sloan-type flushometer)
Applies to: Sloan Royal/Regal-class flushometers (Zurn similar)
What this error means
Per Sloan's own troubleshooting documentation, a flushometer that runs continuously has a diaphragm problem: the bypass hole in the diaphragm assembly is clogged with debris (wash it under running water) or the diaphragm/relief valve is worn — replace the kit. The first response is always the control stop: the shutoff under the chrome cap beside the valve (flathead slot or vandal-resistant key) — turn clockwise to stop the water and end the flood while you sort out parts.
Symptoms
- Water running continuously after flush
- Repeating flush cycles
- Water bill quietly doubling
Try this first (safe DIY steps)
- Stop the water: pop the control-stop cap, turn the screw clockwise until flow stops (newer stops may need the special key — it lives in the maintenance drawer)
- Confident DIYers: shut the stop, relieve pressure by triggering the valve, open the cover, remove the diaphragm assembly, wash the bypass hole clean, reassemble
- Persisting: replace the diaphragm kit — matched to the valve's GPF label (see our kit guide)
Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.
When to call a technician
A plumber's flushometer rebuild visit runs roughly $150–350; the kit itself is $15–55, and the job is 15 minutes with the water off — facilities-savvy offices DIY this one.