A toilet that runs constantly or doesn’t flush properly can be quite a nuisance and waste of water. There are several common problems associated with toilets that are fairly easy to diagnose and repair.

Repairing a Toilet

When you remove the cover of the tank, you’ll notice that the toilet contains an overflow tube to keep it from flooding, a float to control the water level, an intake valve to let water into the tank, and a flapper valve on the bottom that is connected to the handle by a chain.

Inside Toilet.

Often when a toilet won’t stop running, the culprit is that the water level in the tank is set too high. This allows water to spill over the top of the overflow tube and keeps the intake valve from shutting off.

Overflow Tube

Depending on how the toilet is made, the water level in the tank can be adjusted by either turning a screw on the top of the intake valve,

Adjusting water level with a screwdriver.

or by reaching into the tank and turning an adjustment at the bottom.

Adjusting water level by hand.

When you have finished adjusting it, flush the toilet and check to see that the water level remains a bit below the top of the overflow tube.

Another common problem is a gradual loss of water in the tank, which causes the intake valve to cycle on and off periodically. If this is the case, you probably have a leaky flapper valve. To check, pour a little food coloring in the tank.

Adding food coloring.

If the water in the bowl changes color without flushing it, the flapper valve needs to be replaced.

The water in the bowl changing colors.

To replace the flapper, turn off the water to the toilet at the cutoff valve.

Turn off toilet

Flush the toilet to purge the water from the tank. Reach inside the tank and remove the old flapper valve.

Replace flapper.

Replace it with a new one and reattach the chain from the handle.

If neither of these two repairs solves the problem, you might have to resort to replacing the entire inner workings of the tank. Kits are available at home improvement stores that contain all the parts necessary, along with step-by-step instructions.

Toilet Repair Kit

If the problem involves the intake valve, unhook the water line from the bottom of the tank, and loosen the nut that holds the intake value.

Intake valve.

Remove the intake valve and replace it with the new one.

Replace guts.

If the overflow tube and flapper assembly require replacement, the tank will have to be removed from the toilet by loosening the two bolts that hold it in place. After replacing the components, reattach the tank to the toilet. The chain from the handle to the flapper should have a little slack in it, but not so much that it can become lodged under the flapper when it is flushed. When everything is back in place, fill up the tank and check for leaks.

If the toilet leaks at the floor when flushed, the problem lies with the seal between the bowl and drain flange. To repair, remove the plastic caps on the bolts that hold the bowl to the floor and gradually tighten up the bolts. Don’t over tighten and be careful not to crack the base of the bowl.

If it still leaks, the toilet will have to be removed and the wax ring that seals the bowl to the drain flange replaced. See our article on How to Remove and Replace a Toilet for more details.

Editorial Contributors
Danny Lipford

Danny Lipford


Danny Lipford is a home improvement expert and television personality who started his remodeling business, Lipford Construction, at the age of 21 in Mobile, Alabama. He gained national recognition as the host of the nationally syndicated television show, Today's Homeowner with Danny Lipford, which started as a small cable show in Mobile. Danny's expertise in home improvement has also led him to be a contributor to popular magazines and websites and the go-to source for advice on everything related to the home. He has made over 200 national television appearances and served as the home improvement expert for CBS's The Early Show and The Weather Channel for over a decade. Danny is also the founder of 3 Echoes Content Studio, TodaysHomeowner.com, and Checking In With Chelsea, a décor and lifestyle blog.

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