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Intermittent low / no pressure to kitchen tap and washing machine only in borehole system

We have a borehole system, shared with our neighbour.

The neighbours say their water supply is OK, and the water pressure on the outside tap is really good.

The water supply comes into our house and the first thing that comes off is our washing machine, then the downstairs cold tap. Then that supply just goes up to the small-ish cold water tank in the attic.

The hot water cylinder, toilets, upstairs taps and electric shower run off the cold water tank.

The electric shower used to run directly off the water supply rather than from the cold water tank, but we changed it because the shower frequently didn’t have enough pressure to run.

However, for the last couple of years, the water pressure to the downstairs cold water tap has been really intermittent - at some times of day, no water at all comes out; at others it’s just a dribble (takes 2 minutes to fill a pint glass); sometimes it’s absolutely fine. The washing machine virtually never makes it through a cycle without the alarm going off for not enough water pressure coming in to run.

I can’t figure out anything that consistently triggers when the water pressure downstairs is good / bad. There being too much coming off the supply would seem an obvious answer, but there is often no water pressure to the tap at 2am when everyone is asleep so nothing has been used for ages. Sometimes there seems almost to be more pressure on the kitchen tap when water is also being drawn into the cold water tank in the attic, e.g. just after toilet flushed.

When the ‘no / low water pressure’ alarm on the washing machine is going off, I have gone outside to the borehole system and checked whether the pump is drawing water into the pressure tank above the bore hole. It often isn’t. Usually, if a tap is running upstairs for example so the cold water tank is filling, I can hear the pump drawing water to the pressure tank triggering on and off at the points I’d expect it to, so this seems a bit strange.

Any ideas for what we could check / do would be hugely appreciated. I’m happy to call a plumber (obviously!) but am concerned that they’ll turn up at a time when it’s all working fine, so I’d like to be able to figure out possible causes… could it be the washing machine causing issues (even when it’s not on? The kitchen tap sometimes doesn’t work when the washing machine is off). Could it be that water is not being drawn / the pump to the pressure tank not being triggered by the downstairs tap and washing machine (but it is by the cold water tank filling?)

3 Answers from MyBuilder Plumbers

Best Answer

Has your neighbour had any upgrades which could effect your house?

Measure your neighbors Litres per minute with a 'Weir Cup' to see if they're receiving the same flow as you.

Sounds like you're better off have a low pressure tank system (CWST) to all outlets with a whole house pump fitted.

This will guarantee consistent pressures at peak times and all through the day


Answered 22nd Oct 2019

Sounds to me that a valve is possibly blocked. The best thing to do would be to trace the pipe back to a point as far away from the kitchen but within the local and cut in a temporary washing machine valve which can be done while water I’d on and see what pressure is there and work to the taps. I would think there is a blocked isolation valve or half opened valve somewhere on the pipe
Hope this gives an idea to try

Regards Howard Rudge


Answered 22nd Oct 2018

Sounds like you have the very old conventional pipework set up there.
Would be good alternative to call Thames water as I'm sure it sounds like they should hold some responsibility for the water and measures up to your boundary.
It's only worth trying and free advise and cost you nothing.


Answered 28th Jan 2019

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