water tank keeps filling

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Well-known member
Jun 2, 2009
Gainesville, Fl
my water tank keeps filling when hooked up to city water.  I have replaced the fill valve
twice and that did not help.  Someone told me it was the 12v water pump allowing
water to back fill.  Any ideas.


Edit by John:  changed message icon to Topic Solved
It could very well be the pump leaking.  If you can, shut off the water line at the pump, either inlet or outlet, and see if the problem stops.  Most likely the check valve is partially open.
phelpo said:
my water tank keeps filling when hooked up to city water.

That happened to me.  It was the internal check valve in the water pump.  Wasn't a fixable part so I went to Lowe's and got a pvc check valve and installed it in the pressure side line from the pump to stop the backflow.  Required a couple of pvc adapter fittings and a couple of hose clamps.  Total investment about $10.
I'll agree with the others. If it's not the fill valve, it has to be the pump check valve.  This is usually self-evident, though. If the pump check valve leaks, the system would not maintain pressure when using the pump instead of city water. The pump would cycle occasionally for no apparent reason.
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