Check toilet fill valve float height
Running toilet
When the toilet flapper looks fine but the toilet keeps running, set the fill-valve float so water stops below the overflow tube.
A good toilet flapper can still leave a hiss if the fill valve float is set too high and water spills into the overflow. Float height is the next calm check when the toilet keeps running.
Check toilet fill valve float height when the flapper is fine
- Lift the tank lid. Confirm the flapper seats flat and the chain has a little slack (not the issue of the day if those already look right).
- Watch a fill cycle. If water climbs to the top of the overflow tube and dribbles in, the float is too high.
- Adjust the float cup or screw per the valve style so the water line stops about ½ inch below the top of the overflow tube.
- Flush once and watch again. Water should stop cleanly with a quiet tank — no endless trickle into the overflow.
Do not bend metal float arms aggressively; use the designed clip or screw. For the full overflow walkthrough, see toilet water spilling into the overflow tube.
Honest stop
If the valve will not shut off at any float height, replace the fill valve. Keep chasing the flapper only when the rim of the flush valve is the leak path.
More help
- Same niche: Adjust toilet flapper chain slack so it seats flat · Toilet flapper fine — keep refill tube above waterline · Toilet flapper fine — bent trip lever needs a kit not just a flapper · Running toilet — check the supply valve for drips after a fix · Toilet flapper — dual-flush chain tangle keeps toilet running · Toilet flapper fine — dual-flush float can still keep it open · Toilet flapper path — match fill valve to left vs right tank hole · Toilet flapper — set chain slack to about one finger width · Toilet flapper — hold it closed to confirm a leak · Toilet flapper — pencil-mark the tank waterline after a quiet fill · Toilet flapper — seat it evenly with no twist in the chain · Toilet flapper — shut the water off and flush before a swap · Running toilet — skip tank tablets that can wear the flapper · Toilet flapper — tighten the handle nut for partial lift · Toilet ghost flushes or refills on its own · Toilet flapper fine — fix handle bushing sideways play · Toilet keeps running — flapper check first · Toilet still runs after a new flapper · Toilet water spilling into the overflow tube · Toilet flapper — check a twenty-minute pencil-mark drop · Running toilet — wipe the flush valve seat under the flapper · All running toilet guides
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