10 July Closeup of a toilet

5 Possible Reasons Your Toilet is Leaking

Posted by PlumbWize

A leaking toilet is one of the most inconvenient and costly plumbing problems that homeowners face. A common tell-tale sign of a leaking toilet is the formation of a puddle near the toilet or moisture spontaneously forming on the toilet’s tank. Another tell-tale sign is a toilet that keeps running or flushing even when it isn’t used. Under normal circumstances, about 27% of water usage comes from toilet flushing. Therefore, a running toilet due to leakage can have a major impact on your water bill if left unfixed.  

Needless to say, toilet leaks, whatever the cause, need to be fixed ASAP. If you notice that the toilet leak is rapidly progressing or if you have a plumbing emergency on your hands, reach out to our plumbing emergency experts who are available round the clock and try to shut off the water supply to your toilet while waiting. 

However, if you have a minor leak happening with your toilet, you may want to figure out the root cause of it and decide your next steps from there. Well, you’re in the right place! This article covers the top 5 common reasons why toilets leak and how to spot them. 

Let’s get started!


Top image of a puddle forming at the base of the toilet due to leakage


Cause #1: Leaking Supply Line 

What is the supply line? 

The supply line is the part of the toilet that supplies water into the tank of the toilet for flushing. The supply line is typically found outside of the toilet and it connects to two points: the supply valve which is typically installed into the wall and to the toilet’s tank. These lines are usually made of either plastic, vinyl, or stainless steel. Problems can arise when the joints of the supply line become weak or loose due to either wear and tear or accidental physical impact. The solution to this problem is typically to replace the supply line altogether. 

What are the signs of a supply line problem? 

If you have a damaged supply line you will notice a puddle of water forming near the base of the toilet where the supply line is. If the supply line is damaged near the wall, the water may run on the wall and cause staining on the tiles. 

Cause #2: Broken Wax Seal 

What is the wax seal? 

The wax seal is located under your toilet where it serves as an impermeable barrier to keep flushed water and sewage from leaking outside. Since this part is enclosed, the most common reason why it gets damaged is simple wear and tear. Replacing the wax seal is a complicated process that involves actually removing the whole toilet from its place. Out of all the causes listed here, this one involves the most risk and should not be considered for DIY. Slight mistakes in the process can leave you with even worse problems. 

What are the signs of a broken wax seal? 

You’ll know that it’s a problem with your wax seal if there is a leakage forming on the base of your toilet. Additionally, there would be a lingering, unpleasant odour that accompanies it. The toilet may also wobble if this is the problem. 

Cause #3: Damaged Toilet Tank 

What is the toilet tank? 

The toilet tank is a part we’re all familiar with. This holds all the water for flushing as well as the toilet’s flushing mechanisms. Over time, the toilet tank can sustain cracks because of age or physical impact. Fortunately, really small cracks won’t mean that you need to replace your toilet. These can be quickly remedied using a sealer. Larger cracks, however, may get worse and could mean that you need to replace your toilet. 

What are the signs of a damaged toilet tank? 

You’ll know that you have a cracked toilet tank if you can observe unexpected moisture on the tank. These can accumulate into puddles under the tank. If you are unsure that this is your problem, you can find out with this simple trick. Put food colouring in the water of the tank. Wait for a few minutes then check if the colour appears anywhere on the tank or on the bathroom floor. 

Close-up of a cracked toilet tank


Cause #4: Damaged Toilet Float 

What is the toilet float? 

The toilet float is located inside the toilet tank and is the ball that you can see floating on top of the toilet tank’s water. This serves to trigger the mechanism for refilling the water in the toilet tank when water levels run low. When this part is damaged, the fill valve of the toilet tends to run continuously. The common cause of damage to this part is wear and tear or inappropriate handling. 

What are the signs of a damaged toilet float? 

The most telltale external sign that this is your problem is if your toilet runs continuously. With this part damaged, it will signal the fill valve to keep filling. 

Cause #5: Damaged Fill Valve or Flush Valve 

What is the fill valve and flush valve? 

The fill valve lets water refill the tank when water levels are lowered (as signalled by the toilet float). Meanwhile, the flush valve allows the water from the tank to go into the bowl when triggered (typically by the flush lever/button.) These parts get damaged either by wear and tear or by mishandling. 

What are the signs of a damaged fill valve or flush valve? 

A damaged fill valve can cause the toilet to either run constantly or to not (or barely) flush. Either way, it signals that the tank isn’t being appropriately filled – it’s either overfilled or underfilled respectively. 

Meanwhile, a broken flush valve will lead to your toilet running constantly.   

How Safe is DIY When It Comes to Toilet Leaks? 

The safety and effectiveness of DIY toilet plumbing vary per individual case. A lot of it rests on proper diagnosis. Understandably, DIY can be prone to misdiagnosis and this can lead to unnecessary additional costs. Moreover, in cases where the leak could be caused by more than one problem, an expert plumber will be able to assess and fix all the problems in one sweep. There’s also the possibility of damaging replacement parts and poor installation. 

So though DIY can be a tempting option to seemingly save costs, in most cases, it can lead to additional costs and/or further problems down the line. For these reasons, we highly recommend getting an expert plumber for all toilet plumbing issues. 

Where Can I Get Expert Help? 

Here at PlumbWize, our expert plumbers can get the repair done right the first time. If you have a toilet leakage, we can diagnose the cause/s properly and get all the needed repairs done in one go. We service areas around Burlington, Oakville, and Hamilton. 

We also specialize in various other plumbing services including residential plumbing services, commercial plumbing services, Kitec replacement services, frozen & burst pipes repair services, and more. So whatever plumbing problem you’re facing, we got you covered. Contact us today!


Leave a Comment