Toilet flapper path — match fill valve to left vs right tank hole
Running toilet
Before you buy a fill valve on a toilet keeps running path, match left vs right tank hole so the new valve clears the flapper and trip lever.
When a toilet keeps running past a good toilet flapper, a new fill valve must match the tank’s left or right supply hole. Wrong-side kits fight the trip lever and overflow — measure the hole side before you order.
Match fill valve to left vs right tank hole before you buy
- Lift the lid and note whether the fill valve / supply shank sits on the left or right of the tank (from the front of the bowl).
- Measure shank size and height range on the old valve, then buy a universal or side-matched fill valve that lists your hole side or a swivel top that clears the trip lever.
- Dry-fit the new valve so the refill tube reaches the overflow without crossing the flapper chain path.
- Only after side and height clearances look right should you shut water, swap, and set float height.
Honest stop: cracked tanks, seized shank nuts, or leaks at the supply after a swap need a plumber — do not overtighten a plastic locknut into a porcelain tank.
More help
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- Related fixes elsewhere: Check toilet fill valve float height · Toilet keeps running — flapper check