Leak Repair for Toilets Guide

A leaky toilet can cause serious problems in your home. Flooding leads to expensive and even irreparable damage, threatening the very foundation of your house. Not identifying or addressing the leak will only worsen the problem.

By understanding the basic mechanics of a leaking toilet, you’ll see that it’s easier than it sounds and you’ll be equipped to avoid such a disaster.

There are a few reasons why your toilet might be leaking and often you can take care of the issue just with our advice and a little elbow grease. We’re going to guide you through an analysis of your toilet to figure out the problem and steps towards a solution.

Leak Assessment

Although it might look simple, the toilet consists of many well-hidden parts. There are various seals, valves, wax rings, and other parts that all work together to keep your toilet durable and functional.

But damage to any of these parts can result in a leak if you don’t notice it in time.

Cracks and easily identifiable damage to the surface of the toilet are one thing, but sometimes it gets a little more complicated.

A good place to start is figuring out exactly where the leak is coming from. There are typically three possibilities:

  • The bowl
  • Between the tank and the bowl
  • During the flush

All need different approaches!

Before we dive in and start narrowing it down, let’s go through some handy toilet assessment and repair tricks you’ll need for a lot of these repairs.

  • Detaching and reattaching your toilet
  • Taking apart your toilet tank
  • Performing a water color test

Depending on the problem, you won’t necessarily need to do any of this but you’ll be prepared no matter what!

Taking the Toilet Apart

Luckily, this is much easier than it sounds. You’ll need to take the toilet apart if the leak is coming from the bowl. This is also a good opportunity to take a good look at your toilet and spot any other issues. You’ll be safe following our steps but the video above shows a great, detailed walkthrough for both toilet detachment and reattachment.

  1. To start, turn off the water supply to your toilet and flush once. Make sure to hold down the flush lever until the tank empties completely and use a plunger to push leftover water down the drain. Use a sponge to soak up and remove any water still remaining in the tank and bowl.
  2. Then, unscrew the water supply line from the valve to loosen it. Remove the bolts from each side of the toilet, using a wrench and pliers if needed. You will need to detach the tank and then the body of the toilet. Scroll down for a more detailed walkthrough for  tank removal and replacement. Once you’ve detached the toilet, carefully put it aside on a piece of cardboard or towel.
  3. You may notice the sewer gas ponging from the piping, you can use a rag to block the pipe while you’re busy.
  4. Finally, use a putty knife to remove the existing seal, then clear the floor from debris to expose the closet flange.

Remounting the Toilet

After you’ve addressed the issue, you can now remount the toilet. Place the new wax ring over the flange and put the bolts in place. Remove the rag from the pipe and put the toilet in the right position, paying close attention to alignment. You can also check that everything lines up by sliding the closet bolts, ensuring a tight and secure seal.

If the toilet misaligns with the flange or the seal loosens you’ll have the same leaky nuisance on your hands. If everything fits properly, seal the toilet with your body weight.

We advise not to use or move the toilet for a few hours while the new wax ring sets. After it’s securely set, turn on the water supply valve, and when the tank fills up, flush it once to check if it’s leaking. If it is, you might have problems with the connector pipe, which will mean calling a plumber.

Taking Apart the Toilet Tank

To address some of the issues below, you’ll need to detach and take your toilet tank apart. It sounds daunting but have no fear – you are more than capable of pulling it off, for a lack of better phrasing. It’s just an expression though, please don’t actually pull it off. For a smooth dismantle you can instead follow the steps laid out below.

  1. Like when detaching your toilet, start by turning off the water supply line. Flush to empty the tank, plunge if necessary, then use a sponge to remove any remaining water in the tank.
  2. Next, disconnect the water inlet tube from the toilet. Test the supply lines now. If necessary, this is the point where we recommend replacing your washers and supply tube.
  3. If you have a 2-piece toilet, unbolt the tank from the bowl and take a look inside. You will notice that there are two slotted screw heads that you need to remove. If the screws won’t come out, you can use a drill to help remove them, just be very careful with the porcelain. If the screws are rusted or beyond stubborn to remove, check out another of our helpful articles, how to remove rusted tank bolts, for safe removal.
  4. Next, for a 2-piece toilet, lift the toilet tank and peel off the seal. Your old seal is a reference for your new seal and you can buy one just like it when looking for a new, replacement seal. You can pick up a handy tank-to-bowl bolt kit at the same time to help attach your tank with the new seal.
  5. While the tank is removed, make sure the gasket isn’t cracked and everything looks okay. Then, place your metal or fiber washers on the bolt and slide it onto the tank holes. Secure it with a nut to ensure a leak-proof seal.
  6. Take the tank and put it over the bowl, making sure that they are aligned and correctly placed according to the holes. Now, you will need to place your bolts and carefully tighten them.
  7. Finally, it’s time for a leak test! Pour a few gallons of water in the tank before turning on the water supply. Look out for any leaking. If the issue persists, you’ll likely want to call a professional in.

The Water Color Test

The water color test comes in handy when identifying certain causes of leaks, like a problem with your flapper, or your shank gasket, or a leak between the tank and the bowl. For this test, you’ll want a non-permanent water dye. Remove the tank lid and add a few drops of dye to the water. Let it sit for 10 to 15 minutes, and then check the water leaking from the tank.

If the water matches the dyed watercolor from your toilet, you’ll be able to better narrow down the cause of the leak.

Diagnose the Leak

Now let’s get down to the diagnosis. If your toilet is…

1. Leaking Directly from the Bowl

If you suspect your bowl, the first thing to do is check that your toilet isn’t cracked. Porcelain is very delicate and although it’s sturdy, can crack for a number of reasons. A crack is unfortunately a more serious problem that a professional will need to handle.

But if you don’t see any cracks, there’s another problem that you might be able to solve without a plumber’s help. You might need a friend’s help though, especially if you’re a newbie… toilets can get pretty heavy and need to be carefully handled.

Checking the Flange

It’s very likely that if your toilet leaks, you have a problem with the flange. The flange or closet flange is a pipe that attaches to the toilet and secures it to the floor. Replacing the flange is difficult, so the best idea is to install a reinforcement ring and, if you can, avoid getting a totally new flange. In this case, you will need to detach your toilet like we talked about. The video further up shows a great walkthrough for cleaning your flange and replacing the wax seal.

When replacing the seal, simply clean the flange and drill a clearance hole, put fresh caulk around the hole, and place the reinforcement ring over the flange. Bolt it together and wait for 10-12 hours before putting the toilet back.

Flange supports are made of strong materials like steel and screwed around the flange for added reinforcement. That way, the support reinforces the area around the flange pipe and prevents any damage to the integrity of your flooring.

If the flooring in your house is relatively new or was installed after the toilet, the flange might be too low for the flooring. In that case, you will need to install an extender ring. Below you’ll see an example of a flange support ring, and then an extender ring, which helps raise the flange for a better floor fit.

Is the Floor in Good Condition?

While the toilet is removed, make sure to check the area around the flange. Poke it with a screwdriver to make sure that it’s still solid and not rotting. If there are any signs of rot, you’ll need to remove the rotting wood and repair the floor. We recommend then installing a flange support to prevent the rot from returning.

Fixing the Seal

The seal is the most common cause of leaking, mostly because the seal can get easily damaged in a number of ways. Incorrect installation, inadequate maintenance and general wear and tear can put stress on the seal and weaken the air-tight hold.

Another issue might be that the toilet isn’t bolted down properly. As a first step, check both the seal and the bolts to make sure they’re functioning as normal. If the seal looks damaged, you’ll want to replace it completely – to do this, you’ll need to take the toilet apart (see above). If the bolts are loose, tighten them carefully to fully secure the toilet. However, make sure not to overdo it when tightening, or you might break the porcelain.

2. Leaking Between the Tank and Bowl

If the toilet is leaking between the tank and the bowl there are various possible causes. The tank is more complex than the bowl and has more components to understand.

In fact, the source of the water could actually be the toilet tank sweating and not a leak at all. This usually occurs when the temperature of the water inside the tank is lower than the temperature in your bathroom. The warm, moist air condenses on the cold porcelain to form droplets. These droplets can drip to the floor and easily be mistaken for a leak. If you aren’t sure if the toilet is leaking from the tank or if the tank is just sweating, we have a quick and easy water color test to check, remember? Just refer back to our toilet techniques and follow the easy instructions.

If you do confirm that your toilet is leaking between the tank and bowl, there are a handful of tank components which could be to blame. If the water comes from near the centre between the tank and the bowl, you might have to buy a new sponge gasket. If the issue still persists, you might have to replace the washers for bolts. If the toilet leaks even more when you flush, you will have to replace the bowl gasket.

On the other hand, if the leakage occurs from the sides, your washers and bolts are in a bad condition and you should replace them. Ultimately, identifying where your toilet is leaking will help you assess the overall damage as well as which parts to replace. When you buy new parts, ensure that they are compatible with your toilet model.

3. Leaks When Flushed

If your toilet leaks only during flushing, most of the time there are five possibilities.

  • Cracked toilet tank or base
  • Loose supply valve
  • Loose fill valve
  • Flapper dysfunction
  • Loose nuts and bolts

Most of these issues need to be resolved by taking apart the toilet and/or the tank – luckily we covered this way at the beginning – go back and refresh your memory if you need to. Investigate each of these five suspected toilet parts to rule out potential issues.

A toilet leaking from the base could signal further issues. Any cracks in the toilet tank, and in particular the toilet base, are a big cause for concern. You’ll want to call a professional immediately to help fix or potentially replace your toilet in this case.

If the Flapper is the Problem

The flapper is the part of your toilet tank that opens and closes when you flush. Basically, it lets the water go through the pipe to refill the bowl. If the flapper is damaged then the toilet will either leak or flush twice.

Like when we tested the tank, you can test your flapper by adding a few drops of non-permanent water dye to your tank and perform a water color test. If you notice the colored water leaking into the bowl when you haven’t flushed, it means that the flapper is not sitting right. Remove the lid and check the flapper. The rubber should be soft and flexible. If that isn’t the case with yours then it’s time for a replacement. Once the flapper has been replaced, perform a water color test again to make sure it’s not leaking anymore.

Other Possible Issues

Another possible cause could be that your refill tube is too loose, especially if the leakage occurs from the back of the tank. Try to tighten the tube if possible, or you may need to consider a replacement.

As you’re looking for other issues, always be on the lookout for tiny cracks in the porcelain. Unfortunately any cracks are usually impossible to fix, and even if they’re small they will still cause leaks and are likely to just get worse. If you do have any porcelain cracks, you will need to head over to our buyer’s guide and get a completely new toilet.

Shank Gasket

If you can’t decide where the leaking is coming from, it could mean that your shank gasket, or shank washer, is not working properly. The shank gasket is located around the spot where the fill valve attaches to the tank. Since the problem is still tank related, the watercolour test discussed will still work to detect this issue.

When fixing your shank gasket, keep checking for any cracks in the porcelain around the gasket. If everything is fine, simply turn the gasket about a quarter of a turn to tighten it. If this doesn’t resolve the problem then you will need to buy a new gasket.

Water Supply Lines

If you don’t notice water leaking from the toilet itself, you could have a problem with the water lines. If either the inlet or outlet pipes are damaged, they can cause leaking in your basement. You need to make sure that they are properly sealed at all joints and don’t have any cracks.

It’s important that the pipes themselves are actually capable of handling the current water pressure and volume. If there is a problem with your pipes, you will need to either fix or replace them depending on the damage. If you suspect your pipes then it’s time to call the plumber – check out this article to help you find the right professional. Don’t put this call off for too long, this is a serious problem and needs addressing ASAP.

Final Thoughts

Most toilets will spring a leak over time. They’re almost unavoidable. And, unfortunately, leaking can lead to serious problems if left unattended. As you can see though, fixing the leak doesn’t have to be difficult or expensive. Staying careful and closely following the steps will make this a smooth, straightforward process. Many of the materials and tools mentioned are commonly found at most hardware stores, just make sure that what you’re buying is compatible with your toilet. You’ll fix your leaky loo in no time this way!