Loss of mains water pressure

[Shift]

Daughters newbuild house had a leak in the upstairs bathroom today, no isolator valves on the offending taps and stopcock not fully shutting off so turned off at the water meter stopcock in the street.
On turning both back on the gauge on the pressure reducing valve eventually goes upto 4bar but soon drops if a tap is turned on.
I'm guessing either stop cock or prv have become partially clogged with dislodged debris restricting flow or is it possible that the stopcocks not opening up even though the handle is fully open.
Back in the morning with tools but has anyone have any experience of this or any insight please.

 

[CBW]

Just sounds like a restriction/blockage. It’ll be loss of flow rate, not pressure if it’s getting to 4 bar.

 

[Shift]

That's what I'm thinking, either rubber washer come off stopcock or blockage in the prv. Do prv's have a filter.

 

[JohnD]

What shape is the handle on your stopcock or other valves?
(This is not a joke)

 

[CBW]

Do prv's have a filter.

No idea, never installed or worked on them.

 

[oldbutnotdead]

Given your internal stopcock wouldn't turn off its highly likely that it isn't opening fully either (or there's a lump of cr*p stuck in it).
Get it off, have a look-maybe replace it with one of those nice full bore ball valves with a lever on it (not to be mistaken for cheap iso valves)

 

[Shift]

Little stones were in the stopcock and had also blocked the inlet gauze on the pcv. Thanks for the input.