Both of my toilets starting having the same leak at the same time and I can't figure out where it is coming from or how to fix it. The water is coming out from the tank where it meets the bowl and is slowly dripping out the bolt holes. I replaced the bolts and rubber washers that hold the tank to the bowl but the problem continued.

For what it's worth, my furnace went out this winter and the house was 45 or 50 degrees for a week or so and that is about the time when the leak started.

  • Are you sure they're leaking and not just collecting condensation?
    – isherwood
    Mar 21, 2018 at 18:25
  • When our furnace was out, I thought that may have been it. But it has continued since then. Also the water only comes from the bottom of the tank where it meets the bowl.
    – rlltiderll
    Mar 21, 2018 at 18:28
  • 3
    Did you replace the large (3"-4") rubber seal that goes between the tank and the bowl or just the bolts and the bolt seals? Can you put some food coloring in the water to make absolutely sure that it is tank water that is leaking out?
    – JPhi1618
    Mar 21, 2018 at 18:40
  • 2
    turn off the supply line .... see if water level in tank drops
    – jsotola
    Mar 21, 2018 at 23:36
  • When this occurred was anything else done just prior ? The tank main seal could be defective, the tank might be off the seal (budged not seated properly) bolts might not be sealed properly or seated properly . Could have tightened them too much and cracked the tank . Could it be leaking at the inlet line ?
    – Ken
    Mar 23, 2018 at 7:34

1 Answer 1


This might sound strange but sometimes people inadvertently lean against the tank while sitting on the toilet seat. This can put pressure on the large gasket that is meant to seal the tank to the toilet. Even a new gasket can be compressed on the back side near the wall of the ring gasket which could cause leaks on the front side of the gasket. In the beginning of this happening, the leak may stop once a person stands up but eventually the rubber gasket can deteriorate and lose its sealing ability. A possible fix is to avoid leaning back against the tank. Depending on the gasket, it might have to be replaced if it has been damaged from compression. Another preventative solution is to put a proper size board or other solid material that fits the space between the top, back side of the tank just below the lid and attach it to the wall so that if someone leans back, the block of wood can help prevent tank from leaning. Nash Stephens

  • Thanks for the answer; keep 'em coming. And, props for taking our tour before posting; few newbies do. Oct 10, 2019 at 19:04

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