my brother has asked if I can help sort out some plumbing issues, he has a stopcock where the mains water enters the house, conveniently easy access directly under the sink, he has sent me a photo of the setup.

The trouble is that the stopcock wont shut off properly, very hard to turn and when it wont go any further there is still water coming through to the taps, so I am planning on replacing the stopcock (I know this should be in another question but if anyone knows a way of fixing it then that would be helpful).

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As I am planning on replacing it I would like to know what the two items are? that are circled in the photo. If they are not required I'm planing on removing them and tidying up some of the pipe work unless they are required.

I may ask a post another question unless it can be answered here, but there does not seem to be much room at the bottom if the stopcock where it connects to the blue plastic water mains pipe, what would be the best method for making the connection to the stopcock

2 Answers 2


There's some funky plumbing going on there to be sure...

Of the circled devices, #1 looks like a filter of some sort, but that's a nasty way to align the cartridge in terms of having to replace it. But it also appears to have a seal tag on it, as in something official? You might be able to get an answer from the water company on that one.

Circle #2 looks like the pressure regulator valve. It keeps the higher pressure of the utility lines from damaging your internal plumbing and fixtures.

If you can shut the water off at the street, you can remove the stem from that main valve and just replace the washer, seat and packing.

  • Thanks for the info, in the end I was unable to repair the stopcock that was there or remove it without causing major work. For a temporary fix, I placed a second stopcock directly above the one already there. I kept the pressure regulator valve just in case it was required and also removed the filter. The mains can now be turned off using the new stopcock. not ideal but will suffice until I can get it sorted properly.
    – 5202456
    Commented Aug 7, 2018 at 15:09

#1 looks like a surge arrester near the kitchen tap to relieve water hammer. #2 is a pressure regulator which attempts to keep a constant pressure unlike just half turning the stop tap, which would reduce dynamic pressure but not static pressure when there is no water flow, which would be the same as the upstream pressure. A pressure regulator cuts off the house when there is no water flow such that it has a certain static pressure that is not the upstream pressure. The pressure regulator ensures the house is always capped at a certain static pressure and the valve opens when more water is being used (i.e. when there's more dynamic pressure) to keep static pressure constant

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