Quick takeaways
- Drop food colouring in the tank. If it appears in the bowl without flushing → flapper.
- If water never stops trickling into the tank → fill valve.
- Both are 15-minute swaps with no special tools.
Diagnose first
Drop 10 drops of food colouring in the tank, don't flush, wait 30 minutes. If colour appears in the bowl, the flapper isn't sealing — replace it. If the tank water level is rising on its own or the fill valve never shuts off, replace the fill valve. If neither, the flush handle may be sticking.
Related services
Need a Kanata plumber?
24/7 dispatch · flat-rate pricing · local crews