A toilet that keeps running is usually losing water either past the flush seal into the bowl or through the overflow because the fill system is not shutting off. Lift the tank lid and watch a refill cycle before changing anything: water entering the overflow points to the float or fill valve; water leaking into the bowl without reaching the overflow points to the flapper or canister seal, its chain, or the trip lever.
Identify where the water is going
Remove the tank lid carefully and flush. Identify the flush seal (a flapper or canister seal), chain, fill valve, float and overflow tube. Watch as the tank refills and note whether water runs into the overflow tube or leaks from the tank into the bowl. That observation determines which checks to make first.
- Water reaches the overflow: the float may be set too high, or the fill valve may not be closing.
- Water leaks into the bowl without reaching the overflow: the flush seal may not be seating, or the chain or trip lever may be holding it open.
Toilets use different mechanisms, so use the instructions for your toilet and valve rather than assuming one adjustment or replacement part fits every model.
If water is entering the overflow
Adjust the float
When the tank water rises to the overflow, adjust the float so filling stops below the top of the overflow tube. Follow the adjustment method for the specific fill valve. The City of Portland recommends a water level about 1/2–1 inch below the top of the overflow tube; Kohler recommends about 1 inch below. These are model-specific guidance points, not a universal setting.
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While the toilet is filling, gently lift the float by hand. If the water stops, the float setting likely needs adjustment. If lifting it does not stop the flow, the valve may have debris or may have failed.
Check the fill valve for debris or failure
Kohler advises checking for debris at the fill-valve inlet or under its cap and cleaning it according to the valve’s instructions. If the valve still will not shut off after cleaning, replacement may be needed. Choose a replacement fill valve compatible with the toilet; do not assume all designs fit.
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If water is leaking from the tank into the bowl
Check the flapper or canister seal
Inspect the seal over the flush-valve opening. It should sit fully in place and close consistently. Look for dirt, buildup, wear, cracks or misalignment. Cleaning and reseating the seal can resolve a seating problem; if it continues to leak, the seal may need replacement.
For a replacement, compare the old flapper or seal and verify the toilet make, model and flush-valve style. Kohler’s running-toilet repair guide describes common seal checks; the City of Portland’s toilet-leak guide also covers leak identification and repair.
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Check the chain and trip lever
Make sure the chain is not tangled around the float or lever and is not pulled so tight that it holds the seal open. It should have a little slack while still lifting the seal when you flush. A binding trip lever can also prevent the seal from closing properly.
If the toilet runs only sometimes
Intermittent running can still come from a seal that does not close consistently, a binding trip lever, water spilling into the overflow, or debris in the fill valve. Observe the next refill cycle rather than replacing a part based only on when the sound occurs. Kohler Assist lists these possibilities in its guidance on toilets that constantly leak or run and toilets that occasionally leak or run.
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- MADE IN USA - Toilet parts flapper is proudly made in America
- QUICKLY FIX running and leaking toilets and eliminate costly water waste
- HIGH QUALITY REPLACEMENT TOILET PARTS: Need to repair or replace toilet parts? Try Korky Toilet Repair because we continue to commit to designing toilet repair parts that are universal to fit the majority of toilets. Designed & manufactured in Wisconsin.
Choose the repair that matches the symptom
| Observed water path | First checks | When replacement may make sense |
|---|---|---|
| Into the bowl, without water reaching the overflow | Inspect and clean or reseat the flapper or canister seal; check chain slack and trip-lever movement. | If the seal still leaks after cleaning and proper seating, find a replacement compatible with the toilet’s make, model and flush-valve style. |
| Into the overflow tube | Adjust the float so filling stops below the overflow; lift the float during filling to test whether it stops the flow; check the fill valve for debris. | If adjustment and cleaning do not stop filling, a compatible fill-valve replacement may be needed. |
Test the repair
- Flush and watch the entire refill cycle.
- Confirm that water stops below the overflow tube.
- Check that the flapper or canister seal closes fully and consistently, with the chain clear and slightly slack.
- If the toilet still runs, revisit the observed water path and the toilet-specific instructions before replacing additional parts.
If the cause remains unclear or you are not comfortable working on the toilet, getting help from a plumber is a practical option. No single repair threshold applies to every toilet or situation.
Quick Recap
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