You can fix this
Likely cause: a loose supply line connection
Water starting where the supply line meets the tank is usually a loose connection. Snug it by hand with the water off.
Why this happens
This Old House says to check the water supply line first when a toilet leaks, because there could be a loose nut or a leak on the supply hose. Bob Vila says to check for loose connections between the supply line and the fill mechanism, since a simple tightening may fix it. Korky says to hand-tighten the supply line's mounting nut only and to avoid sealants or tape.
How to fix it
- Look at where the water starts. If it is coming from the shutoff valve at the wall itself, do not turn that valve. Shut off the main water supply by hand, without forcing it, and call a plumber.
- Turn off the toilet's own supply stop by hand. If it will not turn, do not force it. Shut off the main water supply instead, also without forcing it, and call a plumber.
- Dry the supply line, the nut and the underside of the tank with a towel.
- Tighten the mounting nut at the tank by hand only. Korky says not to use sealants or tape.
- Turn the water back on slowly, as Korky advises, and watch the connection while the tank refills.
- Wipe the tank, dry the floor, and check again later today. If the beads are all over the tank rather than at the connection, it may be condensation, and drier bathroom air is the first fix, as This Old House says.
When to stop. If the drip returns, if it comes from the shutoff valve or the hose itself, or if the stop will not turn, do not force or tighten anything. Shut off the main water supply by hand, without forcing it, and call a plumber. If water reaches an outlet, plug, cord, switch or light, including a light in the ceiling below, do not touch it and call an electrician, since Ready.gov says not to touch electrical equipment if it is wet or if you are standing in water.
If this does not fix it, tell the plumber
- Where the water starts: the nut under the tank, the hose, or the shutoff at the wall.
- Whether snugging the nut by hand changed anything.
- Whether the shutoff valve turns easily by hand.
Build the full list: what to tell the plumber.
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