The flapper might not fit the toilet. One plumbing-shop proprietor told me his mechanics carry 11 types of flapper valves, including special valves for 1.6-gallon toilets that became standard in 1994.

Also check that the pull chain attached to the valve is not too short; if so, it could be holding the valve slightly open. It's often wisest to replace the fill valve and the flapper at once.

Even if you replace the flapper, it may not fit correctly, or there may be damage to the rim sealed by the flapper. Try feeling around the rim of the flush valve for divots, cracks or deposits.

Many things can go wrong inside a toilet (besides the obvious), but changing these two parts will fix 90 percent of toilet problems. First, turn off the water supply valve under the toilet.

A toilet flapper is a key piece of the appliance's design. A failing flapper is a common reason for leaks, and you should never ignore such problems as they can lead to wasted water and a ...