How to Fix Leak Between Toilet Tank and Bowl

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

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.

Old Gasket

Over time, gaskets can wear out from exposure to chemicals, bacteria, and hard water. If you’ve recently replaced the gasket or flush valve but still notice leaks, check for the following issues.

Unevenly Tightened Tank Bolts

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.

Incorrect Gasket Size

Ensure you have the right gasket size for your toilet. Tank-to-bowl gaskets come in two sizes, standard 2-inch and large 3-inch. If you need to switch to the correct size, check out our tank-to-bowl gaskets.

Start by shutting off the water supply to your toilet, then flush the toilet to drain as much water from the tank as you can.

Next, place a bucket under the toilet's water supply line, and carefully disconnect the water supply line from the toilet tank. You may also need to use a sponge to remove the water remaining in the tank.

Once you disconnect the supply line, remove all old bolts, metal washers, and nuts from the tank. Lift the tank off the base and carefully place the tank on the closed toilet seat. Then remove the old gasket.

After you remove the old gasket, simply place the new gasket over the mounting nut threads of the flush valve.

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 partner apply downward pressure to keep the tank level as you tighten the nuts, alternating sides until the tank is stable.

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

Once the tank is stable, reconnect the water supply line to the fill valve by turning the mounting nut counterclockwise. We recommend hand-tightening this part only and avoiding the use of sealants or tape.

When the mounting nut is tightened properly, slowly turn on the water supply line. While the tank is refilling, check the connection between the tank and bowl to make sure it has a water-tight seal.