Toilets
Why Does My Toilet Randomly Refill?
The short answer
When a toilet refills on its own every few minutes, the tank is usually losing water between flushes. A worn flapper is common, but the flush-valve seal, chain position, or other internal leakage can produce the same symptom. As the tank level drops, the fill valve briefly tops it off.
Common symptoms
- Toilet runs for 10–20 seconds with no flush
- Happens every few minutes or hourly
- No visible leak on the floor
Most likely causes
- —Worn flapper not sealing
- —Flush valve seal degraded
- —Fill valve slowly seeping
Safe things you can check
- ✓Add food coloring to the tank, wait 15 minutes without flushing. If color appears in the bowl, the flapper is leaking.
- ✓Replace the flapper — it's the cheapest and most likely fix.
When to call a professional
If a new flapper doesn't hold, the flush valve seat is likely pitted and needs replacement.
Related professional service
Reviewed by Paul Hall, Owner & Licensed Plumber
The Classic Plumber · Knoxville, TN · License #4268
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