Assessing and Repairing a Cracked Toilet

A toilet in a bathroom

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A cracked toilet is often a confusing plumbing problem because the cracks are not always easy to spot. In some cases, the crack can be present since the toilet was first manufactured, but for some reason may not surface for many years. Other times, a toilet without any cracks can suddenly develop one and start leaking.

Leaks from a cracked toilet can come in many shapes and sizes. When a toilet crack is caused by extreme temperature changes that cause the toilet to crack all the way through and cause flooding, the cause is obvious. Usually, a leak from a cracked toilet occurs slowly, so the source can be relatively difficult to identify.

Cracked Toilet Tank

A toilet tank can have cracks above or below the water level and on the inside or outside. Where the crack is located will determine what action is needed.

  • A toilet tank crack above the water level is usually not a problem unless the crack grows slowly. If you spot a toilet crack in the tank, mark it and keep an eye on it to make sure it doesn't get any worse. It can be useful to take a picture of the crack to refer back to in the future.
  • A crack in the tank that is below the water level will have to be fixed. Unfortunately, a toilet tank crack can be hard to spot. If you suspect a leak from the toilet tank, start by checking the seals between the tank and the bowl. Next, check the tank carefully for a crack in the porcelain. You may have to look on both the outside and the inside of the tank to see it.

Repair Options

If you have a crack in the tank, you may be able to find a porcelain sealer to repair the crack. To use a sealant, you'll need to thoroughly drain and dry out the toilet tank before repairing it, which means you could be down a toilet for a day or two while the repair sets. In that case, the best option may be to replace the toilet.

Cracked Toilet Bowl

A cracked toilet bowl is more difficult to narrow down; keep in mind that the leak may only occur when you flush the toilet, so flush while you check around the bowl for leaks. If you find water on the floor near the toilet, a leak in the bowl is a possibility. It's a good idea to check for cracks in the bowl on a regular basis as well.

  • A toilet bowl crack above the water level will need to be monitored. If you find a crack in the bowl that does not leak at all because it's near an area that does not have water going through it, you might be all right leaving it. Mark both sides of it to make sure it's not growing. A picture can also be very useful for future reference.
  • A crack in the toilet bowl below the water level is much more complicated. The source may be almost impossible to track down because of the shape of the toilet bowl. When the toilet crack is visible in the part of the bowl that retains water, you'll need to replace the toilet to stop the leak.
  • An invisible crack is also a possibility that can present in two ways: standing water outside of the toilet and missing water. A small invisible leak can cause water to settle on the floor at the base of the toilet. In a more uncommon scenario, the water from the toilet bowl will slowly leak out into the drain instead of onto the floor. If the toilet bowl doesn’t seem to be able to hold water, you could have a cracked toilet that leaks into the drain.

    Repair Options

    Unfortunately, a cracked toilet bowl cannot be repaired. If you don’t see any visible signs of a toilet crack and the leak is at the base of the toilet, you can try to reset the toilet with a new wax ring to see if that solves the problem. If the crack is below the water level, the only option is to replace it with a new toilet.

    Note: Toilet cracks can also result from over-tightening the bolts during the toilet installation. A toilet can even crack when tightening the handle, so be careful not to over tighten when dealing with porcelain.