Kohler toilet keeps running: What to Check and What to Do Next

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   Remove the tank lid and observe the water path during a refill. Look at the bowl for a ripple or trickle, the tank for water entering the overflow, and the trip lever and float for movement. Keep hands clear of moving parts and do not force the lever.

   Expected result: Water enters the overflow; the tank level stops but the bowl ripples; the fill valve turns on periodically; or the toilet is quiet with no visible leak after a flush.

   Next step: Use the observed path to choose the seal, fill-valve, or refill-hose check rather than replacing parts at random. If the tank is close to overflowing, limit water damage with the accessible supply stop and arrange service if it will not close.

   Stop if: Stop for a cracked tank or bowl, water on the floor near electrical equipment, a supply stop that leaks or will not close, or a lever, float, or valve that is stuck and would require force.

   Why this matters

   Why: Overflow points to water-level or fill-valve control. A bowl ripple with a normal tank level points to a flapper, canister seal, flush-valve seat, or refill-hose leak. Periodic refilling suggests a slow leak even when continuous noise is absent.

2. Check 2

   Check the trip lever, rod, chain, and flapper or canister seal after the flush finishes. Confirm the lever returns, the chain is not tangled or tight, and the seal sits evenly on the flush-valve opening. If the model permits, gently reseat the seal and remove accessible debris without scratching the seat.

   Expected result: The lever binds; the chain holds the seal open; the seal is dirty, cracked, warped, or misaligned; the flush-valve seat is damaged; or the seal closes evenly.

   Next step: Correct only an accessible obstruction or permitted chain adjustment, then flush and recheck. Consider an exact-model flapper or canister seal only when its condition and model instructions support it; arrange service for a damaged seat or tank connection.

   Stop if: Stop for cracked porcelain, a seal that cannot be reached without removing the tank or valve, a broken trip lever, or any need to overtighten or pry the flush valve.

   Why this matters

   Why: A binding lever or tight chain can hold the seal open. A worn, dirty, or misaligned seal can leak into the bowl. A damaged seat or a seal that closes correctly shifts attention to the fill side or a less visible tank leak.

3. Check 3

   Watch the fill valve as the tank rises. Check whether the float moves freely and whether the valve shuts off before water reaches the overflow. Inspect the accessible valve cap and inlet for sediment only if the model's instructions describe safe cleaning; do not disassemble a pressurized or concealed valve.

   Expected result: Water spills into the overflow; lifting the float stops the flow; the float sinks or sticks; sediment is visible; or the valve continues running with the water level below the overflow.

   Next step: Adjust the water level only using the model-approved adjustment, then flush and verify shutoff. Clean or replace the fill valve only after confirming the exact Kohler model and instructions; do not infer compatibility from appearance.

   Stop if: Stop for a cracked valve body, uncontrolled spray, a supply connection that leaks, a tank that cannot be isolated, or any need to work below the waterline while the supply is open.

   Why this matters

   Why: An overly high level, sticking float, debris, or a defective fill valve can cause overflow or continuous filling. If the valve does not stop despite a correct level and unobstructed float, replacement or professional diagnosis is more likely than further adjustment.

4. Check 4

   Inspect the refill hose and its connection to the overflow or flush valve. Confirm the hose is secured as the model requires and its end is not submerged below the tank waterline. Then observe whether the toilet refills immediately or only after a delay.

   Expected result: The hose end is underwater; the hose is disconnected or aimed incorrectly; the hose is correctly positioned; or the valve turns on again after many minutes without a flush.

   Next step: Reconnect or secure the hose only as the exact model instructions show, then repeat the flush-and-observe test. Arrange service for a leaking valve base, cracked tank, or a hose connection that will not remain secure.

   Stop if: Stop for a cracked hose port, water spraying from a connection, a tank-to-bowl leak, or any need to remove the tank or tighten concealed hardware.

   Why this matters

   Why: A submerged hose can siphon tank water into the bowl and cause delayed refill. A disconnected or mispositioned hose can affect refill behavior. If the hose is correct but the tank still loses water, a flapper, flush-valve seal, valve base, or fill-valve problem remains more likely.

5. Check 5

   Flush the toilet several times and watch the entire refill, shutoff, and idle period. Check for a bowl ripple, overflow entry, a valve that turns on by itself, leaks around the tank base, and a lever or seal that fails to return after repeated use.

   Expected result: The toilet shuts off and stays quiet; the bowl continues to ripple; water reaches the overflow; the fill valve cycles periodically; or a tank connection leaks.

   Next step: If the symptom remains, close the supply stop if it operates normally, avoid repeated flushes, and arrange qualified plumbing service. Provide the toilet model, observed water path, seal and chain condition, water-level behavior, and any leak location.

   Stop if: Stop for uncontrolled overflow, water on the floor, a supply stop that will not isolate flow, cracked porcelain, or any repair requiring tank removal or concealed plumbing access.

   Why this matters

   Why: A quiet tank and still bowl after repeated tests support a successful accessible correction. Continued bowl flow favors the flush seal or tank-to-bowl path, while overflow favors the fill valve or water-level path; periodic cycling can be a slow seal or refill-hose leak.