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6 Reasons Your Toilet May Be Leaking

We may not give it a lot of thought, but the toilet is one of the most important items in our homes. And toilets can develop leaks. Fortunately, it doesn’t happen very often. It would be great if everything in life was as reliable and low-maintenance as a toilet. These things can last for decades. 

But yes, leaks do happen, and that can cause a lot of problems. First of all, it’s a huge waste of water. Toilet flushing accounts for about 30% of the water you use in your home. Now imagine what happens if it leaks. The average leaky toilet can waste around 200 litres per day. Keep in mind that under normal circumstances, a person uses around 350 litres of water per day. 

And it’s not just the waste of water and your utility bills. A leaky toilet can lead to a lot of damage and expensive repairs. A bit of water around the toilet bowl may not seem like a big deal, but the water can get trapped under the toilet and damage the floor surface, subfloors and framing. The longer you wait, the more it will cost you. 

However, if you’re reading this article, it means you want to know what caused the leak in the first place, so here is our list of the six most common reasons your toilet may be leaking. 

Leaking Supply Line

The supply line is what supplies cold water to the toilet tank for flushing. It’s usually located outside the toilet connected at two points: the water supply valve and the toilet tank. The water supply valve is usually installed into the wall, and it’s also referred to as the shut-off valve. Plastic, vinyl, and stainless steel are the most common materials used to make these lines.

If your water supply line is damaged, water will begin to accumulate at the base of the toilet. The damage might be close to the wall, and in that case, water will run on the wall and stain the tiles. 

Leaks typically occur when supply line joints become weak or loose. The supply line’s rubber lining, which is designed to prevent leakage, can also get damaged. This is either from regular wear and tear or physical impact. The solution is to replace it, which is relatively easy to do. 

You’ll first want to turn off the water to the toilet from the valve. Remove the water from the tank by flushing the toilet. There will still be a bit of water left which you can remove with a sponge. 

The next step is to disconnect the damaged water supply line from the valve in the wall and the fill valve in the toilet’s tank. 

Coat the new valve with plumber’s tape and attach it to these two valves securely but don’t over tighten it because that can also cause damage. 

Now it’s installed, and you can test it to make sure the leak is resolved. 

Of course, even if this is a relatively easy repair, if you’re not confident in your skills because of lack of experience, it’s best to call a plumber. As we’ve already mentioned, it’s possible to damage the line from over tightening it. Plus, you have to make sure that you buy the right kind of line for your valves. 

You also want to be certain that the leak is really caused by the water supply line and not some other issue. 

Broken Wax Seal at the Bottom of the Toilet

Another issue that could be causing your toilet to leak is damage to the wax seal located at the base of your toilet. The purpose of this seal is to prevent sewage and flushed water from leaking outside. It might have a hole in it, or it’s simply wear and tear. 

A good indication that your leak is caused by a broken wax seal is the smell. You’ll also see water accumulate at the base of your toilet, like with the damaged water supply line. However, the water leaking from the supply line is clean. In the case of a damaged seal, the water will have an unpleasant smell that lingers in your bathroom. The toilet may also wobble if the seal is damaged. 

The solution is to replace the seal, which requires removing the toilet, so we don’t recommend you do this yourself. First of all, you don’t know for sure if that’s the cause. You might go through a fairly risky and meticulous process without actually resolving the leak. 

Second of all, you might make mistakes that will cause further damage. 

You could try tightening the closet bolts that secure the toilet to the floor, but your wax seal might still be damaged, and if you apply too much pressure when you tighten them, the toilet’s base can crack.

If you call a plumber, they evaluate the issue and reach the conclusion that the leak is caused by a broken wax seal, they will turn off the water and drain the water from the tank and bowl. Then they’ll disconnect the water supply line and remove the closet bolts. 

They’ll remove the toilet and clean the old wax seal from the toilet and the bowl. The flange will need to be inspected for damage. The flange is a pipe fitting – a circular piece of material with multiple holes in it. It connects the toilet to the floor and drain pipe. If it’s broken, it will need to either be repaired or replaced, depending on its condition. 

Next, they’ll replace the wax seal and reinstall the toilet. 

Damaged Toilet Tank

The toilet tank is probably a part you can easily identify – it’s where the flushing mechanism is located, and it holds the water supplied by the supply line. Toilet tanks typically get damaged from accidental impact that results in cracks. Even very small cracks can lead to leaks and water accumulating on the floor. 

Although small cracks may be frustrating because they’re hard to find, they can usually be fixed with a sealant, so you don’t have to replace the tank. 

For larger cracks, you may have to replace the tank because they get worse. If you have a two-piece unit, you’re lucky because then you don’t have to replace the entire toilet. Getting a new tank might even help you save money if you upgrade to a water-saving design. 

To check if the leak is coming from the tank, you can add food colouring to the water in it. Give it a few minutes and check on the tank and on the floor for water of that colour. 

If it turns out the tank has a crack that’s small enough to be fixed with sealant, you’ll first want to shut off the water supply and empty the tank by flushing. Just as we explained in the previous section, there will still be some water in it that you can remove with a sponge. 

The next step is to get your porcelain sealer or epoxy. When you apply it to the crack, you’ll want to start about an inch above the crack and trace slowly through it. Then you can smooth out the sealer with something like a plastic knife and give it 24 hours to dry. 

After the 24 hours, turn the water back on and check if the leak has been resolved. 

Damaged Fill Valve or Flush Valve

When you empty the toilet tank by flushing, it’s the fill valve that lets water from the supply line refill it. The flushing mechanism inside the tank is composed of different parts:

  • The float ball – you usually find float balls in older toilets. They’re attached to a metal rod. As the name suggests, the float ball floats, so when the tank gets full, it rises, and this shuts off the water supply. When you flush, the lever is connected to a piece called a flapper that gets lifted and lets the water from the tank go into the bowl. The float ball drops, and this allows more water to get into the tank.
  • Cylindrical Float – modern toilets have a cylindrical float that can move vertically on the shaft of the fill valve. The mechanism follows the same principles we described above. 
  • Flush valve – The flush valve, flapper, and flush valve seat allow the water to get from the tank to the bowl. 

If there’s a leak, it could be that there’s a problem with one of these components. 

If it’s the fill valve, your toilet will either run continuously or barely flush, which indicates that the tank isn’t getting filled properly – it’s either too much or not enough water. 

Problems with the flush valve will cause your toilet to run continuously. 

Replacing the Flush Valve

To check if the problem comes from the flush valve, you can turn off the water supply and mark the water level in the tank. Then wait for half an hour and check if the level has dropped. If it has, then you’ll need to fix it to avoid wasting water and increasing your utility bills. 

This isn’t very difficult to do. You’ll first need to shut off the water supply, flush, and remove the rest of the water with a sponge – just like we explained in the other sections of this article. 

The flush valve has two bolts by its sides. Those will need to be removed with a screwdriver while holding the nuts on the other side of the bowl with a wrench. Be careful not to apply too much force because it can cause cracks in your tank. 

Now you can remove the tank from the toilet seat so you can unscrew the flush valve. When you replace it, you do these steps in reverse. The new flush valve will also come with detailed instructions, but if you’ve never done this before, it would be best to watch a couple of video tutorials. It’s much easier to understand the process if you see someone doing it. 

Replacing the Fill Valve

To replace the fill valve, you’ll need to go through the same steps of shutting off the water supply and emptying the tank. Then you’ll need to detach the supply line from the tank and remove the faulty fill valve. 

If you have the older model with the float ball, remove the lock nut from the supply valve, this will allow you to pull the entire assembly from the tank. 

Once these steps are done, you can adjust the height of the new fill valve and install it following the instructions that came with the kit. Reattach the supply line and turn back the water to see if this has resolved the leak. 

Problems with the Flapper 

Sometimes the leak is caused by problems with the flapper, which hold the water in the tank until you flush. In the best-case scenario, it’s not damaged, just stuck. This means that you have to lift the lid from the tank and take a look. It might be stuck in the open position, or the chain has slipped off, so it’s no longer connected to the flushing handle. You’ll be able to fix the leak in a few minutes. 

If it’s damaged, you will need to replace it. The good news is that flappers are sold as individual parts, and they’re cheap. They’re simple rubber or plastic devices, but they’re not indestructible. They can crack or warp, so they can no longer serve as effective barriers between the tank and the bowl. 

Bowl Damage

Lastly, your toilet might be leaking because there are cracks in the bowl itself. If the cracks are very small, you may be able to fix them with waterproof epoxy, as we explained with the cracks in the tank. 

But if the cracks are larger, they can expand, and the only solution is to replace the toilet bowl or the entire unit if it’s not a two-part. You also have to consider that the water from the tank is clean, which isn’t the case for the bowl. 

Still having issues with your toilet? Contact MPJ Plumbing Today!

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