How to Fix a Leaking Toilet
One of the most common toilet problems, that is aside from a clogged toilet, 
is a leaking toilet. Why do they leak? Usually for little more than because they have water running through them. Plumbing fixtures, especially toilets are just prone to leaking.
In most cases, a leaking toilet can be fixed but before you can fix it, you have to diagnose the problem. This of course means that you need to determine where the leak is coming from, usually this is pretty easy, though in some instances it can get pretty tricky. Here is what you can do:
How to Find Out Where the Toilet is Leaking
As we mentioned above, sometimes a toilet just start to leak, it can be due to a number of problems including the toilets age, seals and damage. Any time that you are dealing with water, there is a possibility of mis-diagnosis. Water runs through any path of least resistance and often times where the leak appears to be coming from, is in fact not where the leak started. So please be patient as you eliminate possibilities.
The most common areas for leaks to spring up are the base of the toilet, the base of the toilet tank, the top of the toilet tank and the water supply line for the toilet. These are the areas we will want to inspect first, of course use your own judgement as to what may be the most likely area for your particular leak. Let's begin inspecting these areas:
The Toilet Base: Every toilet has a replaceable wax ring located between the floor drain and your toilet. This is used to seal the drain and prevent leaks, though over time the wax can become damaged and allow water to flow through. In many cases this is a result of either old age or a loose toilet which has allowed the toilet to move around and damage the seal.
Start by drying up the floor around the toilet and watch for water seeping out from under the toilets base. This seepage is usually visible to the naked eye but depending on the intensity of the leak it may require some time for the water to become visible.
If you do in fact see water coming out from under the toilet, give the toilet a good wiggle and see if it appears lose(if tightened properly it should not move.). If your toilet was able to wiggle, try using a wrench to tighten the bolts located on each side of the toilet base(usually found under white plastic caps). After tightening, flush the toilet a couple of times to see if the leak continues.
If the toilet is still leaking, you will need to proceed with our instructions on how to remove and install a toilet. If your toilet does not appear to be leaking from underneath, please continue down the page.
The Base of the Toilet Tank: The toilet tank is often subject to a fair amount of abuse that arises from people leaning into it and sitting down to hard and bumping it. All of this movement can cause a couple of potential problems. Allow us to address those.
Between your toilet tank and the toilet bowl, there is a rubber gasket used to seal the area where water flows from the tank into the bowl when a person flushes the toilet. This rubber can wear out over time or become pinched during installation. The first thing you should do is verify that the tank is not loose by gently shaking it.
If the tank appears to move quite a bit when you shake it, that is a good sign of loose bolts which is an easy fix. Simply lift off the tank lid and locate the two bolts inside the tank, these will be on the bottom and should have one bolt on each side with a rubber washer. You may need to turn off the water to the toilet and drain the tank to reach these bolts.
If the toilet tank does not seem to be loose when you give it a shake, you probably have a bad gasket. These are typically in stock at any major hardware store, just be sure to bring your toilet make and model with you in case. Once you have the replacement gasket, turn off the water to the toilet and drain the tank by flushing the toilet.
Once the tank has been drained, disconnect the water supply line from the bottom side of the toilet tank. You will now need to locate the two bolts inside of the tank, on the bottom and remove them. Now you should be able to lift off the tank from the toilet bowl. You should now see the rubber gasket and replace it with the new one that you just purchased.
Once the gasket has been replaced, gently set the tank back on to the toilet bowl, making sure that you do not bend, pinch or damage the new gasket. Once the tank is in place, replace and tighten the bolts in the bottom of the tank. Make sure that you have re-installed the washer on each bolt, this keeps them from leaking. Once those are snug, you can hook back up the water supply line to the backside of the tank. Make sure that the supply line is tight and turn on the water to the toilet.
Now you will need to allow the tank enough time to fill up completely. Once filled, flush the toilet and inspect the base of the tank for any visible leaks.
The Top of the Toilet Tank: A leak from the top of a toilet tank is usually an easy fix. In most cases the leak will be caused by water spraying or splashing against the underside of the tank lid and running down. So, the first thing that you need to do is locate the source of excess water. Here are some options.
Remove the tank lid and see that the small plastic fill tube has not come loose. This is typically a gray or black colored tube about as big a round as a pencil. If it has come loose simply reattach the end that came loose and your problem should be fixed.
This type of leak might also be a result of a bad float. If the float is not working correctly, it may not be shutting off the water in time and causing an overflow. Try removing the lid and flushing the toilet to see how full the tank gets. If you see that the water is filling to the brim or overflowing, try shutting the water off to the toilet, and replacing the float.
The Water Supply Line: It is not uncommon for a water supply line to start leaking especially if it is the older style, hard copper line. Often a small bump or wiggle can cause one of these lines to spring a leak. Here is how it can be fixed.
First, you will need to shut off the water to the toilet at the valve on the wall behind the toilet. If you are unsure whether or not you have turned off the water, try flushing the toilet and make sure that the tank does not continue to fill. Once the water is off, you can use a crescent wrench to loosen the fittings on both ends of the water supply line, there should be one fitting at the valve and on the back of the toilet tank.
I recommend replacing this line with braided flex line which can be purchased at any local hardware store. Once you have the new supply line, reattach and tighten both ends of the new line to your toilet and the water valve. Turn on the valve and watch for leaks. This should have fixed the problem.
Toilet Leaks that May Not be Repairable
It doesn't happen often, but in some cases a toilet bowl and/or tank can develop a hairline fracture in the porcelain. This is most often due to a bad casting at the factory but can also be a result of misuse. In any event, we have found the best fix to be a simple replacement of the problem fixture.
Some hardware stores do carry a porcelain repair kit for these types of cracks, however, it is little more than applying a band-aid to the problem and in our professional opinion should not be considered a permanent fix.
There are of course a number of other types of leaks that can occur. If we have not answered your question here, we encourage you to look around our website or send us an email , being sure to detail the problem you are having and one of our tech's will respond as soon as possible.
If your toilet is clogged, please visit our How to Unclog a Clogged Toilet article for help.
FEATURED REPAIR GUIDES
- How to Unclog a Clogged Toilet
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- How to Fix a Leaking Toilet
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TOILET REPAIR HIGHLIGHTS
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