How to Fix Leak Between Toilet Tank and Bowl

Is your toilet leaking between the tank and the bowl? Over time, the sponge gasket can settle and release tension in the bolts. 

Other environmental factors such as temperature, humidity, or general use can lead to the bolts loosening over time. Cleaning chemicals, bacteria, city water, well water, and hard water can speed up this process.

If you see water leaking down the base of your toilet or pooling on the floor, you need to replace the tank-to-bowl gasket and hardware. This is unlike a running toilet, where the toilet flapper is leaking, and the water would not leak on the floor.

Does this describe your toilet issue?

What causes leaks between the tank and bowl?

The tank-to-bowl gasket creates a water-tight seal between the tank and the bowl. If your toilet is leaking from tank bolts, getting a new tank-to bowl-gasket and hardware kit is the easiest fix.

If you installed a new tank-to-bowl gasket or flush valve that is leaking, there could be a few reasons. Start by checking to ensure you have the correct-sized tank-to-bowl gasket installed.

You can confirm this by taking the tank off and measuring the size of the flush valve opening. Flush valve openings come in two sizes, standard 2-inch, and large 3-inch. You can find a replacement gasket if you accidentally bought the wrong size by viewing our tank-to-bowl gaskets.

Another install-related issue that could lead to a leak between the tank and bowl, is not tightening the tank bolts evenly. When tightening, it is important to alternate sides. This helps you keep the tank level and stable. If not done properly, it could open a path for water to leak.

To better compress the sponge gasket, we recommend having a friend apply even pressure to both sides of the toilet tank. This will help compress the sponge gasket and lower the risk of over-tightening and cracking the porcelain.

Older tank-to-bowl gaskets fail because they deteriorate over time. Cleaning chemicals, bacteria, city water, well water, and hard water are major factors that can cause them to fail. When a leak of this kind begins, a new gasket is needed.

Since removing the tank from the base isn't as common, you might want to consider replacing everything. We recommend our 2X Complete Toilet Repair Kit, which is made of a material that is 2 times stronger.

How to Install a Tank-to-Bowl Gasket

  1. Shut off the water supply to your toilet. Then flush the toilet to drain the water from the tank.

shut off water supply

  1. Place a bucket under the toilet tank to catch excess water.

place bucket under toilet

  1. Disconnect the water supply line, and remove all old bolts, metal washers, and nuts from the tank.

disconnect water supply line

  1. Carefully disconnect the tank from the bowl and remove the old sponge gasket.

Remove toilet tank

  1. Place the new red gasket over the mounting nut threads.

Attach tank to bowl gasket

  1. Carefully set the tank onto the bowl. Use the bolts, rubber washers, washers, and hex nuts to attach the tank to the bowl. Have a friend apply downward pressure to keep the tank level as you tighten the nuts alternatingly until the tank is stable.

Tighten bolts

  1. Do not overtighten the bolts; doing so may cause the porcelain to crack.

do not overtighten

  1. Reassemble the toilet and turn the water supply line back on.

Turn On Water Supply

Toilet leaking between tank and bowl