In Repair & Maintenance

Easily Fix A Running Toilet For Under $50

You may recall that I recently “repaired” my toilet flapper chain with a paperclip. No sooner had I gotten done telling the entire world, when the fill valve began to leak and run water constantly. I was not happy.


Now I had to fix a running toilet but I had no clue where to start. I picked up a Korky Universal Toilet Repair Kit that promised easy, one try installation. For less than $50 and 60-90 minutes of work I could replace my entire toilet guts.

This was necessary since I didn’t know what I was doing, numerous parts seemed old and leaky, and I only have a single toilet in the house.

You cannot mess up or take too long on a toilet repair when there is no second toilet.

I can easily say that the job wasn’t as difficult as I thought and I did manage it within the afternoon but I can understand if you are intimidated because I certainly was.

If you’re in need of a beginner project to boost your plumbing confidence, check out How to Clean a Drain or Changing a Shower Head.

Identifying The Cause Of A Running Toilet

There are a lot of common causes for a toilet to be running constantly. To fix a running toilet, you need to identify why it’s doing it. Otherwise, you may not actually solve the problem.

The Spruce give a pretty good concise guide to finding the cause of a running toilet. But I’ll run through the experience I had as well when I tried to identify my issue.

Checking The Flapper

If you look inside the tank of a toilet, you’re going to see three main parts. The flapper is the big, rubber flap at the bottom center of the tank.

It is connected to an arm by a chain and if you pull the chain up, the flapper should pull up as well.

This is the first test of a running toilet and one of the first major things that could be causing a toilet to run.

Pull the chain to lift the flapper up and then watch it go back down. Sometimes, just doing this will fix a running toilet.

However, if the flapper settles down and the toilet is still running, you may have a worn out flapper.

Test this by pushing down on the flapper with a stick, like a stir stick. If that stops the toilet running, you need a new flapper or a repair kit. 

Be sure to prepare for the hardware store by knowing the brand of you toilet tank since each brand uses a different type of flapper. It isn’t your toilet bowl that you need to know, but your tank’s brand.

If you can’t find the brand name on the tank, take the old flapper into the store so that you don’t have to go back and forth multiple times for a toilet flapper.

That’s just a dumb reason to make multiple trips to the hardware store.

Check The Fill Valve

I know, I’ve probably lost you. But stay with me here because the fill valve could definitely be a reason why you have a running toilet.

The fill valve is the portion where the water comes into the toilet tank, usually on the left side of the tank.

To check the fill valve for a leak, first you need to drain the toilet. Pull the flapper chain up and watch the top of the fill valve for water coming out where it shouldn’t.

All the water should go out the tube at the top. Anywhere else and you’ve got a leak.

Check The Float

The final crucial factor in a fully functional toilet is the float. There are different types of floats on toilet systems.

Whether it’s a lever arm, a bladder at the end of an arm, or a float attached to the fill valve, you can fix a running toilet by fixing the float frequently.

If you checked the flapper and the fill valve and the toilet still runs, look for issues with the float. The float tells the toilet tank when it’s full and shuts off the fill valve.

If you flush the toilet, the float should rise with the water level. If it doesn’t, you should replace the float to repair the toilet.

The Kit To Fix A Running Toilet

If you checked your toilet parts thoroughly and you can’t find any issues, or if more than one of them is bad, then you should replace the whole guts of the toilet.

This is the surefire way to fix a running toilet if you can’t identify the issue.

I used the Korky Universal Kit. It offered an easy installation, update of all the old systems, quieter action, and a service line if something did go wrong.

It contained the toilet fill valve, flush valve, and flapper so I didn’t have to worry about compatibility between new parts and old parts.

Toilet Anatomy

The kit was a guaranteed way to fix a running toilet. The kit also included 3 new stainless steel toilet bolts and the associated nuts and washers.

I only ended up using 2 but the thought toward being truly universal was nice and unexpected.

I was assured by the salesperson that Korky had excellent parts. After opening it, I would have to agree wholeheartedly.

The bolts were stainless steel and the rubber gasket was a high quality and flexible rubber as well. The fill valve and flush valve were easy to install and set to my toilet as well.

Fortunately, since I do only have a single toilet in the house, I didn’t have to test out the help line.

However, I’ve talked to several customers and they’ve told me that the Korky help line was indeed very helpful and good to have as a backup if something wasn’t simple.

But the instructions were easy enough to follow in my case.

Major Steps to Fix A Running Toilet By Replacing The Guts

Removal of the Water

The first step to fix a running toilet is to remove the water from the existing system as cleanly as possible. You do this by turning the water supply off, turning the knob on the wall clockwise to close it until it stops turning.

Once the supply line is turned all the way off, flush the toilet to drain most of the water out of the tank.

You may have to hold the flapper open in order to help the water drain out in order to fix a running toilet. The water will get in the way…and on the floor.

There will be some water left in the tank. To get the water out, you have to loosen the nut that is holding the supply line onto the bottom of the toilet tank and fill valve.

Water will start to pour out and you need to have a bucket underneath, which the instructions helpfully reminded me of.

I would suggest not only having a bucket underneath but also a couple of towels at least nearby.

I found that the water did not drain directly into the bucket but also around it. The towels help keep most of the water cleaned up fortunately.

Gently pull the supply line off and push aside. If you continue to remove the nut that holds it to the fill valve, it comes off easily.

The supply line can’t be removed from the water shutoff so I taped it to the wall in order to keep it to the side.

It would have been a 10 minute repair to replace just the fill valve but, since I had many parts that were old, I continued on.

Once the supply line is unhooked, you can pull out the old toilet fill valve. Throw out the old toilet fill valve and the nut that originally held it on.

There are replacements for both in the kit.

Take off the Fill Valve and Tank

The tank is held onto the bowl by, in may case, 2 toilet bolts. Some toilets may have 3 bolts though so don’t be surprised if yours has more.

To loosen these bolts, I used an adjustable wrench on the bottom nut, since they were on too tightly to turn by hand, and a flat head screwdriver on the head of the bolt.

They took some work to get off since the porcelain lip on the underside of the bowl got in the way.

When they were loose, I was able to lift the tank up and tip it to drain out any remaining water.

Once as much water is emptied as possible, you can remove the tank but make sure to have a trash bag nearby to wrap around the bottom.

With the tank was removed, the bottom of the tank can be accessed and the bolts pushed out completely.

You won’t need any part of the old bolt assembly, since the Korky kit has it all, so toss it in the garbage can too.

Replacing the Toilet Flapper

To remove the old flapper and flush valve, you will need to set the tank on its back in order to access the nut holding it on. There will be a large rubber gasket on the bottom of the tank that pulls off easily.

Once that’s in the garbage, there is a large nut that holds on the toilet flapper and flush valve assembly. Use a tongue and groove pliers, also called channel locks, in order to loosen the nut.

With the nut removed, the old flapper and flush valve can be pulled out to leave you with an empty tank.

The new toilet flapper and flush valve can now be placed into the tank. The flapper from the Korky kit actually sat slightly diagonal, unlike my old one.

I liked that the kit had instructions, with both pictures and words, to describe in detail how to set the new valve into my tank.

There is a rubber washer for inside the tank and a paper washer for the bottom, all held on by another big nut similar to the one that I just removed.

Once the nut is tight, then press the new rubber gasket onto the bottom of the assembly.

MAKE SURE NOT TO OVERTIGHTEN THE NUT or you will crack the porcelain. It should be tight but don’t crank down on it to force it to turn more.

Reattaching the Tank to the Bowl

With the new flush valve and flapper assembly in the tank, the tank can be reattached to the bowl. Gently place the tank on top of the bowl and put the new toilet bolts in their spaces.

There are large rubber washers that go between the bolt heads and the tank to help seal water in the tank. It is vital that you DON’T OVERTIGHTEN THE BOLTS when you fix a running toilet or you will crack the porcelain.

This step is where most of these installations go wrong and the instructions remind you of this several times.

Fix a running toilet without a plumber

This step is far easier to do with two people however it can be managed by one person, like I did, if that person is determined and flexible enough.

Use your hand to gently hold the tank in place and press down slightly.

Then alternate tightening the nuts so that you tighten one a few turns then switch. This makes sure that the tank is on both secure and level.

Once the tank is secure and the tank touches the bowl, stop tightening!!! The tank should not be able to rock anymore if you’ve done it correctly.

One note: Later on, I found that it isn’t uncommon for even properly installed toilet bolts to loosen slightly over time with…use.

If your toilet starts an unexpected leak a few months after you’ve replaced its guts, don’t be afraid to check if the toilet bolts are tight.

If they’ve loosened, your leaking toilet could be fixed with a simple re-tightening of these bolts.

Inserting the New Toilet Flush Valve

Before we get to this last major step, I will warn you that this was probably the most difficult part trying to fix a running toilet.

At one point, I almost gave up and called my dad. There were swear words uttered. Stick it out though because it’s worth it.

The top of the overflow tube on the flush valve needs to be positioned at least 1″ below the nut that holds on the handle and at least 3/4″ above the water line.

A ruler is required; don’t even try it without one. I tried and it was an epic fail. At the same time, it doesn’t need to be perfect so if it’s an 1/8″ off don’t be terribly concerned.

Once it is placed correctly and locked in place, the new fill valve can be placed.

You have to use that same ruler and place the fill valve according to how the flush valve is placed.

Make the new fill valve is the correct height in relation to the overflow tube on the flush valve, about level.

To help you, there’s a diagram included in the instructions so that there are no questions. I had to refer to the diagram several times.

Once the fill valve is the correct height, finish the installation of it by connecting the nut on the bottom of the tank that holds it on.

Just to warn you beforehand, this was officially the grossest part of trying to fix a running toilet. Also, hand tightened the nut if you tend to overtighten fasteners on plumbing projects.

Attach the Toilet Supply Lines and Test

The fill valve is connected to a plastic tube that goes between it and the flush valve. Cut this to length and connect it to the metal clip included with the kit.

I would suggest that you cut it longer than you think you need. This is something that isn’t in the instructions but I know is difficult to deal with later on.

Fully installed toilet parts

Once this is done, you can reattach the water supply line to the bottom of the fill valve. Make sure to tighten this on as tight as possible.

Up until now, I’ve told you not to overtighten over and over again but in this case, make it as tight as possible.

I had trouble with this and can verify that a little silicone caulk around the outside can help prevent any further leaking.

Now, the moment of truth. Turn the supply line back on just a little bit and look for any obvious or large leaks in the system.

Make sure that there isn’t water coming out of the water supply connection, leaking out of the toilet bolts, or out of the middle of the fill valve.

Make sure your overflow tube is at the correct height to function. The water should just reach the top of the overflow tube before shutting off when the float reaches the top of the fill valve.

To check the supply line connections for dripping water I would suggest putting a paper towel underneath the supply connection for few days to look for a slow leak. I found that out the hard way when my floor got wet.

If there are no leaks after the tank fills, give the toilet a couple of flushes. If there still are no leaks, turn the supply water back on to its normal setting.

From there, put the tank lid back on. Pat yourself on the back and grab a beer because you can now fix a running toilet without a plumber!

Still Confused? Need A Video Tutorial?

Final Thoughts

So in total, the Korky Universal Complete Kit lived up to all of my expectations and more. They promised a great help line if I needed it but I never needed it.

I never once had to open up Youtube or call my dad in a panic. These instructions were incredibly easy to use and I was amazed at how simply and clearly they were written.

Not only were the instructions simple, but this system was excellently designed to live up to the word universal, which I am always skeptical of.

All-in-all I was way impressed and I got to cut my teeth on a real plumbing project. As weird as it sounds, this was an excellent first major plumbing project to try out.

It took 60-90 minutes and cost less than $50 to fix a running toilet which is way cheaper than a plumber.

It wasn’t a whole day and I didn’t feel overwhelmed by it. The only potential source of angst is that I now own a pair of 12″ channel locks that I don’t see getting a lot of use from.

But if that’s the worst of the whole project, it was a 100% success. I would recommend it to anybody who wants to do more than replace a shower head and get into more advanced plumbing.

For some reason once you mess with a toilet you feel like you can do anything.