01Dye test and listen
Remove tank lid. Add food coloring to tank water. Wait 15 min without flushing. Color in bowl = flapper leak.
Constant trickle sound = fill valve running. Water above overflow tube = float too high.
Home & DIY
Fix a Running Toilet in 30 Minutes
Flapper, fill valve, float — diagnose the hiss and stop wasting water
35 min5 photographed stepsBeginner
Complete toilet plumbing method: identify flapper leak vs overflow vs fill valve failure, shut off supply, replace $8 flapper (fixes 80% of cases), adjust or replace fill valve, set water line 2 cm below overflow, dye test to confirm, and know when the whole tank needs pro replacement.
What you'll learn
- Hiss after flush = flapper or overflow
- Dye in tank — color in bowl without flush = flapper leak
- Water line should be 2 cm below overflow tube
- Fill valve adjustment before full replace
Inside this course
- Diagnose the runDye test truth.
- Flapper and fill valveThe usual fixes.
- Pass criteriaDone.
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First steps from Diagnose the run
See how every step looks — photo, checklist, and pro tips included.
02Shut off and flush empty
Turn valve behind toilet clockwise. Flush to empty tank. Sponge remaining water — dry work area.
Photo inside tank before touching — chain routing matters on reassembly.
Pro tip. Towels on floor — old wax ring drips happen when you bump the bowl.
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