Plumbing: Stop A Toilet From Running

A toilet that always runs is an expensive nuisance for homeowners. Here's how to troubleshoot and fix a home toilet that won't stop running.

In order to troubleshoot a constantly running toilet, it pays to understand how a normal flushing cycle works. A typical commode consists of two parts- the bowl and the tank. The entire assembly sits on a large pipe which leads to the sewer system. Four anchor bolts hold the toilet securely to the floor and a wax ring helps to seal off any minor leaks around the bowl. A small water line with a large shut-off valve is usually located behind and below the commode itself. A flexible pipe leads the water from this line to the top of the tank, where it refills the tank after a flush.

Whenever someone pushes down on the toilet's handle, a simple arm pulls a chain leading to a stopper on the bottom of the tank. All of the water inside the tank is pulled by gravity into the bowl section. Any water and waste material in the bowl is forced by air pressure and gravity into the pipe leading to the sewer. A certain amount of clean water refills the bowl and the stopper falls back over the hole in the tank. At the same time, an armature leading to a float opens the inflow valve. As long as the water in the tank is flowing out, the float pulls down on the armature. When the stopper replugs the hole on the bottom of the tank, water begins to back up. The float will then be returned to its original position as the water level rises. Once it has reached its highest point, the float causes the armature to shut off the valve from the clean water line and the toilet is now ready for the next flush.

The problem starts whenever one or more elements of a proper flush fail. If the stopper in the tank fails to seal off the water, the level of the water will not rise enough to cut off the incoming water from the line. Sometimes the chain leading to the stopper will become entangled under it, preventing a solid seal. The quick solution is to remove the tank lid and look at the stopper assembly during a flush. There may be too much slack on the chain, allowing it to be pulled under the stopper during a flush. If you observe the chain becoming trapped under the stopper, the quickest fix is to readjust the chain from the arm attached to it. You should be able to disengage the chain and reattach it at a higher link. The stopper itself may also have a leak, so make sure it reseats fully after each test flush. Replace any part which shows signs of corrosion or deterioration.

If the stopper and chain are working properly, the next area to check is the float and valve assembly. Ideally, clean water from the intake water line should begin to flow into a tube as soon as the current tank water is fully released. But what happens during a problematic flush is the water will refill the tank, but the float will not reach its natural high point. The armature won't be in a position to shut off the valve, and the water continues to flow. If this is the cause of the constant running, the fix could be simple or a bit more complicated.

The simplest fix would be to readjust the current float manually. Systems vary from toilet to toilet, but usually the float assembly includes a means to make small adjustments. If the float is not reaching a point where it shuts off the valve, then adjust the float until it naturally floats higher in the tank. The valve should then shut off as designed and the water won't run constantly. If adjusting the float doesn't help, then the problem may lie in the valve assembly leading from the intake line to the armature. This may require replacing the entire assembly, because the valve may have developed a leak which cannot be repaired in place. Fortunately, most hardware and home improvement stories carry the proper replacement parts for most models of toilets.

Removing defective toilet parts will require a few basic tools, some protective gloves and an iron will. Cut off the water intake line by turning the large valve counterclockwise until snug. Flush the toilet several times until all of the water has been removed. Tank water has never been exposed to waste material, but it can develop some icky build-up from years of use. When in doubt, wear rubber gloves. Be sure you have the replacement parts in hand before removing the old ones. The instructions may include removal advice, so read carefully. Remove the entire valve assembly with a wrench or whatever tools will do the job. Follow the manufacturer's instructions on installing a new valve assembly and then restore the water flow. The tank should fill up and be stopped by the new (or old) float. If the water still continues to run, make some minor adjustments on the float as before. A new valve assembly should solve most problems without the need for a professional plumber. If the problem continues even after replacing all the internal parts, a plumber's advice may be necessary.

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