On Jun 23, 1:58*pm, "Toby" wrote:
Thanks for the detailed advice chaps, I think I will do neverwas'
stopcock experiment first. What seems to happen is the tap that is
put on first at full whack will have minimal debris, while the tap
that is opened second (also at max but with a trickle flow) will be
filled with it. I guess when I get home I'll have to play around and
see what happens when both taps are on at half power etc.

Ok, just went home for lunch hour and tested this out. Whether or not
the tap in our side passage is opened first or second, it is the tap
which is allocated the pressure. So, if I run the kitchen tap full
whack then nip outside and open the side passage tap to full, it comes
on at full pressure while the kitchen tap will trickle. And
interestingly, a load of dirt comes out of the side passage tap at the
high pressure in addition to the kitchen tap's dirt content with the
trickle flow.

I hope I'm making sense, I'm finding this tough to explain...

Makes sense to me!

Just had another thought - what type of boiler do you have in your property?
Is it a sealed system with a pressure guage on or near the boiler?

If so, what is the pressure showing on the gauge when all your taps are off,
then again after you turn the water off in the road and then run the taps to
relese any pressure in the system?

Toby...

No, its not a sealed system, regular old boiler....