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Toilet tank refills after sitting, but what should I check first?
What’s the simplest way to narrow down a toilet that occasionally refills without anyone flushing it? I’d want to know whether the tank’s water level drops while it’s unused and whether water is reaching the overflow. Would those observations help distinguish a flapper leak from another route for water to enter the bowl, and what role could the fill valve play?
Which checks can help distinguish water leaking from the tank into the bowl from a problem elsewhere, without taking the toilet apart? I’m also unsure when an intermittent refill is enough to justify replacing a part versus calling a plumber.
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2 replies
While the toilet sits unused, compare the tank’s water level with the overflow: water spilling into the overflow suggests the fill valve may be letting the tank overfill, while a falling level below the overflow points toward water leaving elsewhere. A few drops of food coloring in the tank can help: if color appears in the bowl without flushing, water is likely leaking from tank to bowl, often past the flapper. These clues narrow it down, but don’t prove the cause.
I’d replace a part when the checks point to a specific, simple fault and the repair is within the owner’s comfort level. If the cause is still unclear, the refill continues, or water is visibly going where it shouldn’t, I’d call a plumber rather than swap parts by guesswork. The occasional nature of the symptom makes a clear diagnosis especially useful before deciding.
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