When I run my downstairs kitchen sink cold water tap, water begins to run into the pan of my upstairs toilet. This can then only be sorted by flushing it. But it doesn't happen all the time, maybe only twice a day. Any ideas?
Yes John has a point but my thoughts are if the valve is the plastic type when purchased they have two valves or plungers whatever you like to call them, one for high pressure and the other for low pressure [loft tank fed] it seems it's a mains fed cistern with wrong one and has the low pressure one in it instead of the high pressure so when there is a flow it could cause the cistern valve to open slightly.
Nobby
April 2008
Its obviously a water pressure differential that is upsetting the fill valve on your loo, causing it to overflow. Best to replace them as a whole rather than faff about with washers.
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