DIY - How To Fix A Leaking Toilet

Leaking toilets are not just an inconvenience, they unnecessarily increase your water bills and lead to extra wear and tear. Fortunately, they are relatively simple to fix, and the repair can be made by anyone who is willing to try a few DIY steps.

In general, there are two main reasons that a toilet will leak: a flaw with the ballcock assembly, or a problem with the flapper. In this article we will discuss a few different things you can try to determine what exactly is causing the leak, and what you can do to fix it.

A basic pair of slip-joint pliers is the only tool you will need to complete this, and you’ll want to pick up a couple inexpensive materials including a ballcock assembly and a flapper. 

Ballcock Assembly

1. Inspect the Inlet and Float Valve

You’ll want to take a good look inside the tank to determine if the water is above the overflow tube. If the water level is too high, it is a strong indication that the inlet valve on the ballcock is malfunctioning. This can cause the water to continue rising until is spills into the toilet through the overflow tube. Another cause of too-high water levels could be a problem with the float. You can determine which of these is at fault by holding the rod that lifts the float as you flush the toilet. Keep an eye on the water levels; you will know that the inlet valve is working properly if the water stops. In the case the fix is quite easy – simply adjust the float.

2. Adjust Float

The ballcock will have a small screw at the top that allows for the float level to be adjusted. By either loosening or tightening the screw you will be able to adjust the level that the water will rise to. If water continues to run into the overflow tube after this adjustment, this indicates that you have a faulty float. This can be caused by a few different things, but the main cause is a small hole that prevents the float from floating. Fortunately, this is another simple and inexpensive fix.

3. Replace The Assembly

If you discover that the float is working properly, the next thing to do is to replace the ballcock assembly. The first thing you’ll need to do is turn off the water at the shutoff valve. This will prevent the water from filling up the tank after you flush the toilet. You can remove any leftover water with a towel or sponge. The next step will be to remove the supply line that is connected to the bottom of the ballcock. You can then remove the nut that secures the ballcock to the tank using your slip-joint pliers. You should now be able to easily remove the old ballcock assembly from the tank, and replace with the new one. Be careful not to overtighten the nut, as this could lead to a cracked tank! The last step is to clip the refill tube into place, and turn the water back on.


If you’ve determined that the water does not rise above the overflow tube, the other thing to check is the flapper. You can test to see if this is the cause by simply turning off the water supply and waiting to see if the water leaks out of the tank. Wait around 15 minutes, and if there is noticeably less water left, it may be that the flapper chain is keeping the flapper from sealing in to the seat. It could also indicate that there is a leak in the flapper itself.

1. Test The Chain

To determine whether it is the chain or the flapper that is at fault, you’ll first need to drain the tank, as discussed above. Simply turn off the water and hold the handle down while flushing. Don’t worry about a bit of remaining water in the tank. Now make sure that the chain allows the flapper to fully seal into the seat. If the chain is too short, it will create a small gap between the flapper and the seat. In this case, a new chain is very inexpensive and easy to replace.

2. Replace Flapper

If the chain is long enough to allow for a full seal between flapper and seat, the cause of the leak is likely due to a flawed flapper. Wipe the flapper clean with a cloth and inspect for cracks or tears that would allow water to seep through. If you see even a small split, simply replace it with a matching flapper by attaching it to the hinges at the bottom of the overflow tube.

If you have tried all of the above solutions and find that your toilet is still running, it may be time to call in the professionals. But hey – you can still brag to your spouse that you know the basics of how your toilet works now. Happy DIY’ing!