How to Fix a Running Toilet in 30 Minutes

Overview

A toilet that runs between flushes usually has one of three simple problems: the flapper is not sealing, the tank water is set too high, or the fill valve no longer shuts off cleanly. You can identify the cause by watching one flush and making one adjustment at a time. Most repairs require no plumbing experience, and replacement parts are inexpensive when matched to the toilet before installation.

Step-by-step instructions

1. 1

   Watch a complete flush

   Remove the tank lid carefully and set it on a folded towel. Flush once, then watch the chain, flapper, float, fill valve, and overflow tube as the tank refills. The flapper should lift freely and settle flat; the water should stop about one inch below the top of the overflow tube.

   If the exact cause is unclear, add several drops of food coloring to the tank after it fills. Wait ten minutes without flushing. Colored water in the bowl confirms that the flapper or flush-valve seat is leaking.

2. 2

   Check the chain and flapper

   Make sure the chain has a little slack when the flapper is closed. A chain pulled tight can hold the flapper open, while too much slack can tangle beneath it. Rehook the chain one link at a time and test the handle.

   Press lightly on the closed flapper. If the running stops, shut off the supply valve, flush to empty the tank, and sponge out the remaining water. Unhook the old flapper and take it to the store so its mounting style and size can be matched accurately.

3. 3

   Clean and replace the seal

   Wipe mineral deposits from the flush-valve rim with a damp cloth. Install the new flapper according to its package directions, keeping the chain free of the float and fill-valve arm. Restore the water, allow the tank to fill, and test two or three flushes before moving on.

4. 4

   Set the correct water level

   If water flows into the overflow tube, lower the float. On a cup-style valve, use its adjustment screw or clip; on an older ball float, turn the adjustment screw rather than bending the arm sharply. Set the shutoff level at the tank’s marked water line or roughly one inch below the overflow opening.

   Flush again and let the tank refill completely. The fill valve should stop decisively, without a hiss or a thin stream entering the overflow tube.

5. 5

   Replace a fill valve that will not shut off

   If adjustment does not stop the flow, shut off the supply and flush the tank empty. Disconnect the supply line beneath the tank, loosen the fill-valve locknut, and lift out the old valve. Keep the bucket below the opening to catch remaining water.

   Set the replacement valve height so its critical-level mark sits at least one inch above the overflow tube. Tighten its locknut by hand, reconnect the supply without overtightening, attach the refill tube to the overflow clip, and set the final water level after restoring the supply.

6. 6

   Test for a quiet, dry finish

   Dry the supply connection and tank underside, then watch them through several flushes. Repeat the food-coloring test after the tank settles. No color in the bowl, no water entering the overflow, and no hiss after refill confirm the repair.

Common pitfalls & troubleshooting