• Share:
Parts of a Toilet
Toilets have moving parts, and moving parts wear out or break. If your toilet won't stop running, try repairing or replacing these key parts of the toilet.

By the DIY experts of The Family Handyman Magazine

Finding the problem is usually simple

A toilet runs constantly because the fill valve that lets water into the tank isn't closing completely. A toilet runs intermittently because the valve opens slightly for a few minutes. In either case, you have to figure out why that valve isn't stopping the incoming water flow and if there are broken parts of the toilet that need attention.

First, look for leaks. A leak in the tank can make a toilet run constantly or intermittently. If your toilet is leaking, you've probably noticed it already. But take a look just to be sure. If you find leaks coming from the tank bolts or flush valve, you'll most likely have to remove the tank from the bowl so you can replace the tank bolts, the rubber washers and the gaskets on the flush valve. If there are leaks around the fill valve, tighten the locknut (see Photo 6). Leaks can come from cracks in the tank, too. In that case, the only reliable solution is a new toilet.

If you don't find any leaks, lift off the tank cover. At first glance, the array of submerged thingamajigs inside may look intimidating. But don't let them scare you. There are really only two main parts: the flush valve, which lets water gush into the bowl during the flush; and the fill valve, which lets water refill the tank after the flush. When a toilet runs constantly or intermittently, one of these valves is usually at fault.

To determine which valve is causing the trouble, look at the overflow tube. If water is overflowing into the tube, there's a problem with the fill valve. If the water level is below the top of the tube, the flush valve is leaking, allowing water to trickle into the bowl. That slow, constant outflow of water prevents the fill valve from closing completely. We cut away the fronts and backs of new toilets to show you how to replace these parts of the toilet. Your toilet won't look so pristine inside. You'll find scummy surfaces, water stains and corrosion. But don't be squeamish—the water is as clean as the stuff that comes out of your faucets.

Repair the fill valve. Fix 1: Adjust the float

If your valve has a ball that floats at the end of a rod, gently lift the rod and listen. If the water shuts off, you may be able to stop the running by adjusting the float. Some fill valves have a float adjustment screw on top (see Figure A below). If there is no adjustment screw, bend the float arm. If you have a Fluidmaster-style fill valve, make sure it's adjusted properly (Photo 8). You don't have to empty the tank to make these adjustments.

Parts of a toilet

Parts of a toilet

Get to Know the Inside of Your
Toilet Tank
This cutaway photo highlights the parts of a standard toilet.

Repair the fill valve. Fix 2: Flush the valve

Hard water, debris from old pipes or particles from a break in a city water line can prevent a flush valve from closing completely. Running water through it from the supply line will clear the debris. Photos 1 and 2 show you how to do this on one common type of valve. Even though other valves will look different, the clearing process is similar. However, you may have to remove a few screws on top of the fill valve to remove the cap.

Repair the fill valve. Fix 3: Replace the washer

When you remove the cap to flush out the valve, inspect the washer for wear or cracks. Replacing a bad washer is cheap and easy. But finding the right washer may not be. The most common washers are often available at home centers and hardware stores. Other styles can be hard to find. If you decide to hunt for a washer, remove it and take it to the store to find a match. Plumbers usually replace the whole fill valve rather than hunt for a replacement washer.

Repair the fill valve. Fix 4: If you can't fix the fill valve, replace it

Replacing a fill valve requires only a few basic tools (an adjustable pliers and a pair of scissors) and an hour of your time. A kit containing the type of valve we show here and everything else you need at home centers and hardware stores.

Your first step is to shut off the water. In most cases, you'll have a shutoff valve right next to the toilet coming either through the floor or out of the wall. If you don't have a shutoff, turn off the water supply at the main shutoff valve, where water enters your home. This is a good time to add a shutoff valve next to the toilet or replace one that leaks. This is also a good time to replace the supply line that feeds your toilet (Photo 6). A flexible supply line reinforced with a metal sleeve costs about $7 at home centers and hardware stores. Photos 1 – 8 show how to replace the valve. If the height of your valve is adjustable, set the height before you install the valve (Photo 5). If your valve is a different style from the one we show, check the directions. After mounting the valve (Photo 6), connect the fill tube (Photo 7).

The fill tube squirts water into the overflow tube to refill the toilet bowl. The water that refills the tank gushes from the bottom of the fill valve. When you install the valve and supply lines, turn the nuts finger-tight. Then give each another one-half turn with pliers. When you turn the water supply back on, immediately check for leaks and tighten the nuts a bit more if necessary.

Fix the flush valve

When a flush valve causes a toilet to run, a worn flapper is usually the culprit. But not always. First, look at the chain that raises the flapper. If there's too much slack in the chain, it can tangle up and prevent the flapper from closing firmly. A chain with too little slack can cause trouble too. Photo 3 shows how to set the slack just right.

Next, test the flapper as shown in Photo 1. If extra pressure on the flapper doesn't stop the running noise, water is likely escaping through a cracked or corroded overflow tube. In that case, you have to detach the tank from the bowl and replace the whole flush valve. Since the overflow tube is rarely the cause of a running toilet, we won't cover that repair here.

If pressing down on the flapper stops the noise, the flapper isn't sealing under normal pressure. Turn off the water, flush the toilet to empty the tank and then run your finger around the rim of the flush valve seat. If you feel mineral deposits, clean the flush valve seat with an abrasive sponge or ScotchBrite pad. Don't use anything that might roughen it. If cleaning the flush valve seat doesn't solve the problem, you need to replace the flapper.

Replacing your flapper may require slightly different steps than we show (Photos 2 and 3). Your flapper may screw onto a threaded rod or have a ring that slips over the overflow tube. If you have an unusual flush valve, finding a replacement flapper may be the hardest part of the job. To find a suitable replacement, turn off the water, take the old one with you to the home center or hardware store. (Turn off the water before removing the flapper.) You may not find an identical match, but chances are you'll locate one of the same shape and diameter. If not, try a plumbing supply store (in the Yellow Pages under “Plumbing Supplies”) or search online.

It helps to know the brand and model of your toilet. The brand name is usually on the bowl behind the seat. In some cases, the model or number will be on the underside of the lid or inside the tank. Matching an unusual flapper can become a trial-and-error process. Even professional plumbers sometimes try two or three flappers before they find one that works well.

Loosen the retaining nut

Loosen the retaining nut

Install the new handle

Install the new handle

Replace a broken or corroded toilet flush handle

Toilet flush handles are another part of a toilet that can cause toilets to keep running. Often handles get loose or corroded and no longer pull the flap up or drop it back down properly. It’s an easy repair, but there’s a trick to getting the flush handle out. The retaining nut inside the tank is a reverse thread. So, if you’re in front of the toilet, turn the nut to the left to loosen (Photo 1). Then remove the old handle and lever, slide the new handle into place, and thread on the retaining nut. Tighten by turning to the right (Photo 2).

Back to Top

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Tape measure
    • 4-in-1 screwdriver
    • Adjustable wrench
    • Bucket
    • Locking pliers
    • Pliers
    • Shop vacuum

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • Flapper
    • Valve washer
    • Fill valve
    • Toilet handle and retaining nut

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 7 of 7 comments
Show per page: 20   All

September 18, 1:24 PM [GMT -5]

Replacing the fill valve wasn't too much of a problem except for one thing.
The old lock nut on the bottom of the tank would not budge when trying to loosen it. A person at a local hardware store suggested lightly tapping it with a screwdriver and hammer. 10 minutes of that yielded no results. I then tried a small hacksaw and cut on an upward angle most of the way through the lock nut. A couple of light taps with the screwdriver in the cut caused the nut to split open. Only minutes to finish the job after that. [I forgot I owned a Dremel tool and could have ground down the lock nut in no time!]

November 08, 9:10 PM [GMT -5]

Since you said that when lifting the float up quiets or stops the hissing, then it has to be in the fill valve. Do you have the fill valve that has the big ball float on a long arm? Or do you have the fill valve that has a plastic float that rides up and down the fill valve? In either case, there probably is screws on top of the fill valve, or the other kind has a cap on top which you squeeze and turn to get it off. There could be a bad seal, or some sediment not allowing it to seal good.

February 13, 1:23 AM [GMT -5]

I am detecting some wetness at the bottom of the tank, around the valve, though it doesn't seem to be dripping. I want to make sure there's no leak there... what's the best course of action?

June 22, 11:26 AM [GMT -5]

I took these steps on an old toilet in our house that was difficult to flush (you really had to push down hard on the arm). We couldn't replace the toilet outright because it's a perfect match (light tan) to the sink that's right next to it. Modern colors don't seem to make so we're stuck with it. After replacing the innards, the toilet is like new.

In the future, I might upgrade to the two stage flushing system (either liquids or liquid & solids) to reduce the amount of water used per flush. But at this point, since I'm on a well it's not a priority.

June 03, 12:03 AM [GMT -5]

Excellent pictures and images.

May 20, 8:51 PM [GMT -5]

This is very informative....would give this a full thumbs up.

I have a question though.

I have this issue wherein there is a hissing sound on the refill valve once after the toilet bowl is flushed. Once water is filled, it would take 15 minutes before it dies down. I could not bend the plastic arm of the floating ball as this is ribbed and is hard that it may break. Further to that, there is no leak detected on the tank, as well as on the flapper/flush valve and the overflow pipe as the water level is 1IN below the top.

I countinued various tries - I flushed the toilet after water valve is turned off. Turned it on and adjusted the pressure, and still hissing sound is present. I then adjusted the floating ball almost positioning it at the end of the threaded portion, and still hissing sound could be heard. I as well replaced the floating ball, to no avail.

All in all with all these tries and experiments, it still takes 15 minutes for the hissing sound to disapper. I can tell that it does come from the refill valve because if you tap its end or somehow lift the floating ball, the hissing sounds stops immediately.

Is this normal? Hope to hear from you soon. Thanks!

Is this normal? Or should I just replace the entire refill valve.

April 28, 4:04 AM [GMT -5]

Thanks! This is going to save me all sorts of money.

+ Add Your Comment

Add Your Comment

Parts of a Toilet

Please add your comment

Log in to My Account

Log in to enjoy membership benefits from The Family Handyman.

  • Forgot your password?
Don’t have an account yet?

Sign up today for FREE and become part of The Family Handyman community of DIYers.

Member benefits:

  • Get a FREE Traditional Bookcase Project Plan
  • Sign up for FREE DIY newsletters
  • Save projects to your project binder
  • Ask and answer questions in our DIY Forums
  • Share comments on DIY Projects and more!
Join Us Today

Report Abuse

Reasons for reporting post

Free OnSite Newsletter

Get timely DIY projects for your home and yard, plus a dream project for your wish list!

Follow Us

Featured Product

Buy Now