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Toilet Repair: How to Fix a Leaking or Running Toilet

Dan, a licensed electrician, has been a homeowner for 40+ years and has nearly always done his own repair and improvement tasks.

Learn how to fix a running toilet.

Learn how to fix a running toilet.

Repair a Running Toilet Yourself

Sooner or later, everyone will find they have a leaky or running toilet that needs repairs. You might hear water running constantly, or maybe it cycles on and off. Maybe the flush isn't powerful enough, or perhaps the bowl doesn't refill as well as it used to. Rubber gaskets harden and no longer seal, parts corrode and plastic pieces finally crack and leak, floats develop holes and fill with water . . . there is a myriad of reasons that a toilet might leak and run.

It's not an emergency, but a running toilet does need to be fixed. Water bills can escalate into the stratosphere or electric bills can rise if you are on a private well and pump your own water. Don't put it off longer than necessary.

Toilet repair is a simple task and does not require an expensive plumber. Almost no tools are necessary (all you need are some pliers, rib joint pliers, and a bowl to catch the excess water) and it should not take over ½ an hour at the most. In almost all cases, the installation of a simple repair kit is all that is necessary.

Below, you'll find answers to these questions:

  1. Troubleshooting: Why is your toilet running?
  2. Which kind of toilet repair kit should you buy?
  3. Which parts do you need to replace?
  4. Which is the fill valve and where is the flapper?
  5. How do you turn off the water to the toilet?
  6. How do you install each part?

Step 1: Check for Leaks and Obstructions

The first thing to do is check the inside of the toilet tank for obvious problems.

  • If the toilet is running constantly, it could be something as simple as an obstruction keeping the flapper from closing.
  • If there's a float arm (a flotation device attached to a metal arm), hold it up while the tank fills to see if the water stops. This arm might have gotten bent. Make sure it's adjusted at just the right angle so the tank stops filling when the water level reaches just below the top of the overflow pipe.
  • The chain between the flush lever and the flapper valve could be tangled, holding the flapper open. Untangle it if that seems to be the problem.
  • Flush the toilet and watch to see if there are any leaks. If you see water leaking around the flapper and into the bowl, or if you use a long stick to press down on it and notice that the water stops running, then it will need to be replaced.

If you don't find a leak or any of these types of physical obstructions, then the problem is likely your stem valve or a flapper that does not seal. Continue to step #2.

Parts from the new kit: flapper valve on the left and fill valve stem on the right. These don't match my old parts at all, and it doesn't have a float ball, but it will work fine.

Parts from the new kit: flapper valve on the left and fill valve stem on the right. These don't match my old parts at all, and it doesn't have a float ball, but it will work fine.

Step 2: Buy the Right Toilet Repair Kit

The most common parts that need replacement are the valve assembly and/or the flapper valve. Both of these parts will be included in the kit. In rare cases, the plumbing where the flapper sits might be bad, but this is unusual.

Which toilet repair kit do I need?

Some repair kits are specific to the brand, model, or size of the toilet tank, but most are universal and will fit nearly any toilet. If at all possible, find one that is a "fit anything" kit—they truly do fit very nearly every toilet out there and you don't have to worry about tank size or special fittings.

Do I have to replace both parts, even if they're not broken?

While you may need nothing but a flapper, it is probably wise to replace the fill valve assembly at the same time. Most kits contain both parts at a minimal cost, so even if you only have to do part of the job, you might as well replace all you can with new parts. If your toilet is old enough to have worn through one piece, the other parts are probably not far behind. These parts tend to wear out and get corroded after about five years.

Which flapper fits my toilet?

If you opt to replace just the flapper, you should know that they mostly come in two sizes: 2" and 3". In general, older models (pre-2005) use the 2" ones and newer ones the 3". Look at the flush valve drain (the thing the flapper seals to) at the bottom of the tank. Is it about the size of a tennis ball? Then go with the 2". If it looks more like a softball, go with the larger one.

Which fill valve replacement part will fit my toilet?

If you choose to replace just the fill valve, this is a universal part. This assembly controls the amount of water that flows into your toilet's tank. The package should include the fill valve assembly, refill tube, and the nuts and gaskets required to complete the job.

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Read More From Dengarden

This is where you turn off the water to the toilet tank. This hose is braided metal—a good idea as it is not likely to ever burst.

This is where you turn off the water to the toilet tank. This hose is braided metal—a good idea as it is not likely to ever burst.

This is the original water valve, the one I need to replace.

This is the original water valve, the one I need to replace.

Step 3: Install the New Fill Valve

  1. Behind the toilet, you'll find a hose or pipe going from the wall or floor up to the tank. Shut that valve off clockwise and hold the flush lever down to drain the toilet.
  2. Place a bowl or pan under the hose fitting and unscrew the hose from the bottom of the tank. There will be some (clean) water that drains out. You may need to use pliers to turn the hose fittings, but it isn't usually very hard to unscrew.
  3. Remove the tank lid and pull the small tubing out of the overflow pipe. (This is just a small piece of tubing that goes from the valve arrangement into the open end of the overflow pipe near the center of the tank.)
  4. Unscrew the large nut at the bottom exterior of the tank that holds the valve assembly in, and pull the valve up and out from inside the tank.
  5. Following the instructions that came with your particular replacement valve, set the new valve into place and screw on a new nut under the tank. Adjust the height of the stem to fit. Pliers will help with the final bit of tightening but don't over-tighten this nut, since these are usually made of plastic or nylon and can be broken if tightened too much.
  6. Fasten the water supply hose back onto the valve fitting where it protrudes under the toilet tank.
The old valve assembly has a float ball, but the new one doesn't. It should still work fine.

The old valve assembly has a float ball, but the new one doesn't. It should still work fine.

The new water tube from the valve to the overflow tube has been installed.

The new water tube from the valve to the overflow tube has been installed.

Step 4: Install the New Flapper Valve

  1. Remove the old flapper valve by either working it off of the supporting overflow tube or simply cutting it off (it will cut easily with scissors).
  2. Replace it with the new one. Some new flappers come with a chain attached, while others will use the old chain. Either way, the chain between the flush lever and the flapper needs to be loose enough so that it will not keep the flapper raised, but tight enough so that pressing the flush handle will raise the flapper. There should be about half an inch of slack in the chain.
  3. Make sure to thoroughly clean the "seat" where the flapper will try to seal onto. Make sure there isn't any slimy stuff that will prevent it from sealing.
  4. Kits with a float ball generally require bending the rod that connects the float ball to the valve, while kits without that ball generally require raising or lowering the top of the valve assembly. Your instructions will tell you just how to do that in either case.
  5. Turn the water back on and let the tank fill. Generally, the water level should be about an inch below the top of the overflow tube, but if you are uncertain, most toilet tanks clearly mark where the water level should be with a ring around the tank.
  6. Flush the toilet and watch to make sure the flapper is sealing properly and the chain doesn't get caught underneath it.
  7. Replace the tank lid, and you're done!
The old valve is removed, giving a good view of the flapper in the center of the tank.

The old valve is removed, giving a good view of the flapper in the center of the tank.

Frequently Asked Questions

What if my toilet runs intermittently?

If the water seems to be turning off and on (the "phantom flush"), you probably have a slow leak from your tank into your bowl. You'll need to replace the flapper or the flapper seat/flush valve drain (the thing the flapper seals to).

What if my toilet is running all the time?

  • It could be the fill tube (the little hose that squirts water into the overflow tube) is not adjusted properly. It should be positioned about an inch above the rim of the overflow tube.
  • If you have a bar float, this controls the water level in the tank, so you should make sure it's bent at the right angle. The water level in the tank is controlled by an adjustable float. If it's too low, you'll have a wimpy flush; if it’s too high, the water will overflow the tube and the fill valve won’t shut off.
  • The flapper might not be sealing properly—either it's an old part or there's something preventing it from sealing.
  • The fill valve and/or flapper might need replacing.

Do I need a ball float or not?

It doesn't matter. There are two different styles of valve assemblies—with or without a ball float: They both work and they're interchangeable.

What if I have a dual flush button-flush toilet?

The button-flush units work a little differently. See the instructional video below for step-by-step instructions.

What if my toilet doesn't have a flapper?

If you don't see a flapper, you might have a Kohler canister-style unit. See the video below for repair instructions.

Is It Hard to Fix Your Own Toilet?

Fixing a toilet is a very easy task that can be accomplished by almost anyone. Even if you have to buy a pair of pliers, they can become the beginning of your own tool kit and the cost of the pliers will still be far cheaper than bringing a plumber in. It should only take you about a ½ hour at the most.

If your toilet flushes with a button...

If you open the tank and don't see a flapper...

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: My toilet flushes and the water tank empties and refills, but the toilet bowl drains to almost nothing. What can I do to refill the toilet's tank/bowl?

Answer: There should be a large tube in the tank, with a small hose going to it from the valve assembly. This is to fill the bowl. Make sure it is connected and goes into the tube. Some kits will have a small valve on that hose to limit the amount of water going through it as well to make sure water isn't wasted overfilling the bowl; make sure it is not closed.

© 2011 Dan Harmon


Dan Harmon (author) from Boise, Idaho on July 29, 2019:

Aw, c'mon Ken. I replaced the valve assembly (but not the flapper valve) in my father-in-laws toilet a week ago - it took about 10 minutes. Though I will say that his was exceptionally simple with very little differences between the two and no problems shutting off the water or removing the supply hose.

Ken Burgess from Florida on July 29, 2019:

Plenty of info here, this covers the bases, not that its the easiest thing in the world to do, it can be a pain in the behind, but the alternative is a HUGE water bill.

Dan Harmon (author) from Boise, Idaho on January 05, 2014:

Can you shorten the chain just a bit and still have it long enough to work? Just cut off a few links or leave the extra at the top where it fits onto the handle? That usually fixes that problem.

Blogger at Best from Detroit MI on January 05, 2014:

I just did change my toilet repair kit and I must say it feels like a rock feel of my heart. That annoying running water noise was just killing me everyday. I did change the kit and I no longer have the ball in the toilet bowl but I am recently experiencing the chain getting stuck under the drain and makes the water still leaking, and I have to tap the paddle a little and it fixes the issue do you have any idea on how I can fix this issue? Thanks in advance

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