Toilet Problems and Repair Guides

How a toilet works

A standard gravity toilet is a tank of stored water sitting on a bowl. When you press the handle, a lever arm lifts the flapper at the bottom of the tank. Water rushes into the bowl through the rim jets, and gravity carries the waste down the drain. As the tank empties, the flapper drops back and seals the flush valve.⁠[1]

The fill valve then takes over. Its float drops with the water level and opens the valve; as the tank refills, the float rises and shuts it off. A small refill tube from the fill valve to the overflow tube tops up the bowl at the same time.⁠[1] The overflow tube has a second job: if the fill valve fails to shut off, the water spills down the tube into the bowl instead of over the rim of the tank.⁠[1]

On a two-piece toilet, a sponge gasket under the flush valve seals the tank to the bowl.⁠[1] A seal under the bowl, often a wax ring, keeps water and sewer gas from escaping where the toilet meets the floor drain.⁠[2]

So almost every toilet problem traces back to one of a few places: the flapper or flush valve, the fill valve, the chain and handle, the seals, or the drain below the bowl. Fluidmaster's first question for a running toilet is simply which of the two tank valves is at fault.⁠[3]

Toilet safety basics

Find the shutoff valve behind each toilet now, and check that it turns. It is the fastest way to stop an overflow or a leak.

Keep sewage at arm's length. Fargo's water department warns that contact with household sewage is a serious health risk and says to avoid it.⁠[5] Wear gloves for any clog or backup, and keep children and pets away.

Lift the tank lid with both hands and lay it flat on a towel before you work in the tank, so it cannot slide or get stepped on.

Common toilet problems and the first check

Each first check takes a few minutes and tells you which guide to open.

Toilet upkeep and expected life

Test for silent leaks once or twice a year. The EPA's dye test takes 10 minutes: a few drops of food coloring in the tank, no flushing, then look for color in the bowl. Flush right after, so the dye does not stain the tank.⁠[6]

Replace the flapper before it fails. The EPA says to check it periodically and replace it at least every five years, because an old or worn flapper can make a toilet flush on its own or leak thousands of gallons a year without a sound.⁠[6] The EPA says most toilet leaks come from old or worn flappers, and that household leaks can waste 180 gallons a week.⁠[7]

Keep bleach and chlorine tablets out of the tank. Fluidmaster warns that in-tank drop-in cleaners with bleach or chlorine can damage tank components.⁠[3]

Flush only toilet paper. Fargo's list of sewer blockage causes includes objects flushed down toilets and products labeled "flushable" that do not break down, such as wipes, paper towels and diapers.⁠[5]

Know what lasts. A 2007 NAHB study gives toilets an unlimited life, while the parts inside the tank need occasional maintenance.⁠[8] When a toilet does need replacing, the EPA says toilets account for nearly 30 percent of an average home's indoor water use, and older models can use as much as 6 gallons per flush. WaterSense labeled toilets use 1.28 gallons per flush or less.⁠[7]