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A closed main shutoff still lets water through
If a house main shutoff is closed, but water still reaches a fixture after the pressure in the lines has drained, how should that be interpreted? Does continuing flow suggest the valve isn’t fully shutting off, or could there be another explanation?
Would the next step depend on whether it’s a gate valve, ball valve, or another type? I’m also curious what can be checked safely without forcing a stiff or corroded handle. At what point is it better to leave the valve alone and have a plumber assess or replace it?
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2 replies
A short dribble can be water left in the pipes draining out. If flow continues after that has stopped, the main may be passing water, though an alternate feed or cross-connection is another possibility; the valve style alone can’t establish the cause. Don’t force a stiff or corroded handle - if flow persists or the valve won’t operate safely, have a plumber assess it.
Valve type mainly changes how it’s operated and what a plumber inspects, not what continued flow proves. A gate valve typically takes several turns; a ball valve usually closes with a quarter-turn. Either can fail to shut fully, and don’t force one that’s stiff or corroded. Knowing the type may help a plumber assess it, but it doesn’t rule out another feed or cross-connection.
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