A tap which leaks more when supply isolated

veryintrigued

We have a downstairs kitchen tap which drips a little most of the time.

Conscious of this when we went away a few weeks ago we shut the two valves, just pre sink hoses under the sink, which feed this tap.

Guess what - this increased the water drippage and didn't stop for the full week!

Fast forward to today and we have the water board at the end of the road and they are repairing a leak in the road.

As part of this leak they have had to isolate our whole road.

And guess what - our downstairs tap is now, once again, dripping at a faster rate than normal!!  For hours and looks set to continue!

No other tap does this and the toilet is now not even filling due to the water being cut off.

How can less pressure actually increase the tap leak?

Have we discovered a spring or osmosis or magic trick?

Or have we gone bonkers?

jonnydeppiwish!

Do you have a header tank?

veryintrigued

And now the water company have fixed the leak and advised us that all is good and we should have normal pressure again.

And guess what.

The dripping has stopped!!!

So increased water pressure = less dripping?!

bris

If you have a leaking tap you need to change the tap washer. The tap will not leak if you fix it.

veryintrigued

jonnydeppiwish! said:

Do you have a header tank?

No.

And the dripping tap is only cm away from the stopcock and only metres away from the mains pipe.

We've filled up every utensil and bottle going so are struggling to understand that all this volume is from internal supply

veryintrigued

bris said:

If you have a leaking tap you need to change the tap washer. The tap will not leak if you fix it.

That doesn't answer the question though does it?

The tap (and full kitchen) will be ripped out in two months.

The question why isolation of the tap (by either stopcock, our hose valve, drive tap or waterboard isolation up the street) makes it drip quicker remains.

bris

It does answer the question, water is passing into you house through the mains and the tap leaks because it's faulty. 

There is nothing mysterious about it.

veryintrigued

@bris I'd suggest you put your readers on and have another go.

marcia_

bris said:

It does answer the question, water is passing into you house through the mains and the tap leaks because it's faulty. 

There is nothing mysterious about it.

 After the water has been isolated? 

By both the OP and the water board! 

Bendy_House

Is this a ceramic tap?

 It's not unheard of for these to leak (more) when there's reduced pressure to a partly-worn tap, as the mains pressure actually pushes up on the bottom ceramic disc and helps it to seal against the top one. Reduce the pressure, and they part = leak.
You might even notice that ceramic taps are more stiff in operation with a high mains pressure, for the same reason. Turn the mains off, and they become loose.
(You are now going to tell me it's a conventional tap...)

400ixl

It will be because the water pressure is putting pressure on a component to close the leak and when the pressure is reduced this seal is not as good.