Good flow diminishes in 2 sec to just under 2 litres per min (5mm stream). Suspect blockage in supply pipe. Can one deduce how far away the blockage is? It would help to know where best to start digging!

The water company's stopcock is about 30 yards away from my house. The neighbour's stopcock is near mine but her house is 40 yards away from her stopcock and she gets good pressure and constant good flow. Old records show that the water pipes were 1" originally iron and this seems likely from age of house. The company's stop cock can be seen to be a brass valve with round iron handwheel which fits the hand nicely and is amazingly easy to turn, spindle dribbles a bit. I dug down my side of the company's stopcock access hole expecting to find pipe but I hit rough concrete up to 9" downstream. A plastic coupling feeding a blue pipe is half concreted over so I can't see what sort of pipe connects the stop tap to the plastic coupling but I suspect it might be old iron. My supply pipe branches to feed house and an old shed but both have the same characteristic - ie initial high pressure and flow which diminishes to a miserable trickle in about 2 secs. Where the supply enters the old shed it's in 15mm copper, where it enters the house it's modern grey plastic with push-fit plastic couplings - looks like the eqivalent of 15mm copper. The water company has advised me that if they visit and find the problem lies my side of their stopcock they will charge me for visit and labour to correct. They suggest I uncover my pipes myself or get a contractor to do it. The company stopcock is about 40 yards along a narrow footpath from the nearest vehicle access track which is steep, rocky and unsuitable for anything bigger than a landrover. (Hence contactors would not be able to get diggers in but I could do it manually with considerable effort. However it could mean breaking up concrete steps down from footpath to house. (Path and house on steep side of valley). I think it is possible that although the ends of the pipes are modern it may be only short lenghts with iron in between. So (sorry this is rather long) I was hoping there might be a way determining how far away the blockage is from the short time taken for flow to diminish from quite satisfactory to nearly useless. This would help me to deduce where to dig or perhaps have a good pointer to the problem being just downsteam of the stop cock in which case I reckon the water company should sort it and without charge - but they might not agree!

Thanks for your thoughts. I was afraid there might not be anything to do other than start digging as you suggest.

As to the grey pipe - it's visible on both sides of the in-house stoptap which one can only get at by removing a section of screwed skirting board which then reveals a ragged hole bounded by conctrete blocks and rough concrete in all directions. Upstream comes under concrete path to front door, bounded by rockface on one side, house wall on the other. Downstream disappears under concrete floor of kitchen so it has to stay. There is no risk of accidental physical damage because the concrete is is substantial. The building and plumbing was altered about 14 years ago - is there likely to be a long term problem?

Problem now solved. I started digging at the downstream side of the water company's valve and uncovered about 4' of blue pipe, then I excavated by hand under the pipe. With the benefit of sloping ground I was able to wash round most of the pipe and checked out the mass of concrete which had been put beside the company's valve. Chipping away at the concrete (fortunately a rather weak mix with lots of cavities) I exposed enough of a short ancient rusty iron pipe coming away from company valve to believe the pipe probably had so much rust inside it that it was cause of problem. I rang water company to say that I couldn't renew this short bit of pipe without risk of damage to their valve and said valve was also leaking at it's spindle. They said they'd come out sometime in next few weeks to look but wouldn't specify a date, then came unannounced and asked neighbour to explain the problem. Happily she knew what to say. They told her there might be a bill for part of the cost but that was over a month ago so I am optimistic in that respect and delighted with the new pressure and flow - enough for an electric shower. Yippee! Many thanks to you for your thoughts which helped me to have a go at investigating further and pressing water company to get on with it.