Easy fixes for a running toilet

A running toilet is not only annoying to listen to, but it's also a waste of water. The most common causes of running toilets are easy to fix without calling a plumber or replacing the toilet.

Your toilet's fill valve does a simple job — it allows water into the tank after you flush, and shuts it off when the tank is full. Its action is controlled by a float — either a traditional ball-shaped float or an internal float within the fill valve (more likely in modern toilet units). If too much water enters the tank, it runs over the top of the overflow valve and into the bowl — wasting water and causing a noise nuisance.

• If you have a modern toilet, you can adjust the maximum height of the float by pinching the contacts on either side of the inlet valve and moving the float up or down to the correct level.
• If you have a traditional toilet with a ball-shaped float on the end of an arm, you'll find a small screw to set the maximum float height on the end of the arm.

The flapper is simply a soft rubber disk that opens and closes the flush valve. Flappers have a limited lifespan and are the most common cause of toilet trouble. When a flapper leaks, it allows water to constantly trickle down to the bowl. That in turn causes the fill valve to stay partially open. The result is a toilet that runs constantly.

To avoid wasting water while you make repairs, turn off the water supply to the tank. If the water supply valve won't close, don't worry; you can still perform the following steps.

• Lift the flapper and run your finger around the opening where the flapper contacts the flush valve. The opening should feel smooth. If the opening feels rough, that's due to mineral buildup that is preventing the flapper from sealing completely. Gently clean the opening with a scouring pad.
• Don't scrape off mineral deposits with any type of sharp metal tool. If you damage the opening, the entire flush valve will have to be replaced.
• If the opening feels smooth, the flapper is at fault. Remove it and take it to the store. Choose a flapper that closely matches the old one.
• Install the new flapper, allow the tank to fill and flush the toilet. You may have to adjust and readjust the slack in the chain before the toilet flushes properly.

A fill valve allows water to refill the tank after a flush. A malfunctioning fill valve won't close completely, so water constantly flows into the tank. The result is the same as with a failing flapper: constant noise and wasted water.

• Look at the overflow tube. If water has reached the top of the tube and is trickling into the tube, the fill valve is at fault.
• Even if you have an old float-ball style fill valve, you can replace it with a newer style.
• Replacing a fill valve isn't difficult, but requires some plumbing know-how. If you don't have experience making plumbing connections, leave this task to a pro.

If a crack appears in the bowl or tank, there's little you can do but replace them. Don't feel obliged to replace (rather than repair) your old siphon-type tank mechanism with a new low-flow unit. While newer tanks use less water for each flush, they are slightly more prone to leaks between the tank and bowl.