How to Stop a Leaking Toilet Tank


There is nothing more upsetting than finding water on the floor around your toilet. Thoughts come to mind about raw sewage, and that’s pretty gross. Fortunately, it’s usually not a broken seal between the sewage pipe and the toilet.

Even if it is just water, you need to find out why and stop the leak. Several things could be the cause. All of these issues can be resolved by yourself if you feel confident. If not, then contact a qualified plumber to make the necessary repairs.

Here is a tutorial on how to stop a leaking toilet tank:

1. Fix Condensing Toilet Water

This is a common cause of water on the floor. Condensation forms on the outside of the toilet tank, drips and pools on the floor around the toilet’s base. This sweating is because of the temperature differences where the water inside the tank is cold, and the room temperature is warm. It is a nuisance but easy to fix.

You can purchase tank liners to install on the inside of the tank that insulates the water from the outside temperature. These work pretty well. You can also connect an anti-sweat valve that mixes warm and cold water to bring the temperatures closer together.

After using one or both of these fixes, dry the floor and monitor for any new water. If there is still an issue, it’s time to look for other problems.

2. Stop Cracks in the Toilet Tank

Do a visual inspection of the tank to see if you notice any cracks. This is where water can escape, but unfortunately, the only real way to correct it is by replacing the tank itself. If it’s within the budget, you may want to replace the whole toilet. Then you are assured that there will be no more leaks.

3. Fix Toilet’s Leaking Shut-Off Valve

This is where the water comes in from the wall. You can feel around the valve for water or condensation and if you find any, try to tighten the valve onto the pipe. You can also replace this valve if need be.

4. Repair Toilet’s Water Lines

The water lines run from the toilet to the valve and screw on with specialized nuts. They can become loose and allow water to find its way out, so start by tightening these up. If that doesn’t work, you can shut off the water, unhook the lines and see if the washers need replacing. They sometimes become brittle and crack, so they no longer make a tight seal. Replace them and reconnect the lines. This should solve the problem in this location.

5. Fix Tank-to-Bowl Connection

Sometimes. a leak can come from the connection between the tank and bowl. This is bolted tight with a rubber gasket, but that doesn’t mean it isn’t susceptible to wear and tear.

Here is a tutorial on how to fix the tank-to-bowl connection:

  • Turn off all the water lines and have a shallow bucket at the toilet base to catch any water.
  • Flush the toilet and hold down the lever to drain as much water out as you can. You can now remove all the bolts that connect the two pieces and unhook the water lines.
  • Pull up the tank and remove the sponge gasket. If you don’t already have a replacement, buy one and put it in place.
  • Gently connect the bowl back on with the nuts, washers and bolts and tighten until it’s stable. Don’t tighten too much, as you can crack the porcelain.
  • Reattach the water lines and turn them on. Watch for any water leaks. Hopefully, this has fixed the issue.

6. Check for Leaks under the Toilet

If all these steps have failed to stop the leaking, it may be underneath the toilet. If wastewater is getting in, you must fix this immediately. This will require replacing the wax ring. You can pick these up at your local home supply store.

Here are your next steps to fix the toilet:

  • Start by draining the toilet, turning off the water supply and unhooking the water lines.
  • You will take the nuts from the bolts at the toilet’s base and lift the toilet off the floor. You may need to cut off the calking around the base.
  • Remove the old wax ring and give everything a good clean. If you need to replace the flange bolts or any damaged flooring, plug the open hole and make your repairs.
  • Put the new wax ring on top of the flange, centred on the hole. Position the toilet over the seal and feed the bolts through the holes on the sides.
  • Gently twist it into the wax with some pressure until it is flat on the floor. Replace the bolts tightly, reattach the water lines when you are done.

In the end, you will have diagnosed and repaired the issue of your leaking toilet. Now you can confidently sit on your throne, knowing that it is leak-free and ready for action.