How to Fix a Leaking Toilet

Toilet with a leak at the base

A leaking toilet can be an annoyance and an expense. The water you lose from a toilet leak could cost hundreds of dollars per year if it goes unfixed.

Don’t panic. If you follow these simple steps, even the least experienced handyman can fix their leaking toilet.

Step 1 – Locate the Toilet Leak

If you have water on the bathroom floor, the leaking toilet is due to a defect in the bowl. On the other hand, if you have a constantly running toilet, you may have a toilet leak in the tank. Lift the lid off the leaking toilet tank and put a few drops of food coloring into the water. Do not flush. You will see the colored water escaping into the bowl, this will confirm your suspicions that the leaking toilet is due to a problem with the tank.

Step 2 – A Toilet Leak from the Bowl

It is extremely rare for the porcelain toilet bowl to have cracked. If it has, the whole bowl of the leaking toilet will need to be replaced. However, it is more likely that the seal which joins the base of the bowl to the drainage throat is defective. In this case, the leaking toilet can be repaired by stopping the supply of water and cleaning the surfaces that need to be joined. Simply replace the sealant and wait for it to set before restoring the water supply.

Step 3 –A Toilet Leak from the Tank

If the leaking toilet is caused by a toilet tank problem, then you should lift the lid and “fine tune” the adjustments of the components. Observe a complete flush and check that none of the mechanisms are catching on each other.

If this doesn’t fix your leaking toilet, then either the refill valve or the flush valve must be at fault. To determine which, you will have to do a little more detective work:

  • Shut off the water supply to the leaking toilet and mark the water level inside the tank.
  • Leave it for around half an hour and come back to observe whether it has risen or fallen.

If the level of the water has fallen, your flush valve has broken. These are often made of rubber and susceptible to perish due to the use of bleach and other “in tank” cleaning chemicals. If you stop the water supply and fit a replacement in accordance with the manufacturer’s instructions, the leaking toilet can be easily repaired.

If the level of water has not fallen but the leaking toilet is still a problem, the refill valve is at fault. Check the float (ball cock) for buoyancy – it may have become waterlogged. If the existing float cannot be fixed, a replacement can be fitted in accordance with the manufacturer’s instructions.