Loss of incoming supply a mystery

We were without water incoming for over 8 days. Welsh Water confirmed all OK in the road up to our stopcock and attributed it to frozen pipes under our garden. The gauge on our pressure reducing valve (PRV) immediately after our stop tap under the sink was showing zero, not surprisingly, and the incoming supply (black plastic pipe) was clearly not frozen for the short length we could see coming out of the kitchen floor. The pipe was completely unseen outside and there is no outside tap anywhere near the incoming supply. 8 days later and with all ground frost gone for several days we still had no water. The stoptap under the sink had been opened and closed numerous times.

Then, suddenly the PRG gauge rose and very dirty water started to flow, eventually coming clear. This was at 9pm and no-one was in the road anywhere doing work. Welsh Water say they did nothing and I measured the incoming water temperature as soon as I could and it was 5.5C. I therefore cannot believe this was a frozen pipe issue.

Naturally I'd really like to know the cause so that I can be sure it will not reoccur or get any fault fixed.

The only thing I did to possibly cause this restoration of supply was to fully open and close then restore the PRV but I did this about 10 mins before running water was restored. Could there have been debris which blocked the valve? But why did this not immediately cure when I opened the valve? Is there another explanation?

Incidentally the PRV has worked fine in the 8 months it's been fitted, to reduce pressure to prevent our electric shower's plastic pipes repeatedly exploding. It's set to about 3 bar.

Are you sure that your supply doesn't run through a neighbours property? They might have building work going on and turned it off? Can you check if the stop cock is the right way round, as it could be fitted back wards which could stop the flow?

Andy

This is something I intend to check, but coming on at 9pm after 8 days being off, and checking in the street to verify no-one working nearby at the time it came back led me to conclude this as being unlikely.

You don't get dirty water from a frozen pipe.
I think the water may have been turned off and that your stop cock may be fitted back wards, so when the water came back on again the jumper/washer in the stop cock shut closed.

Remove the stop cock and fit a lever valve, that way you know that the above can't happen (again).

Andy

That sounds very plausible, and reassuring of my belief it did not freeze. But why did it suddenly come back? I did turn the road stopcock off and on but that was 3 hours before it came back. Would it have taken that time from being turned off and on for it to pass water again?