This is one we came across on a refurb some builders were dong in Clapham – splitting 2 flats into 3. What they’ve done here is come off the ‘drain-off’ on the on cold mains pipe, and run a flexible 15mm pipe up to the top floor?!
An old Victorian stop-cock in the pavement outside, feeding a shop and now three flats, with 2 of the flats sharing one of the mains going to the upstairs. The flow rate will never be enough, if all three flats had a tap open, and the shop, there is going to a trickle of water coming out of every tap…if anything at all.
What they should have done was have 4 new stopcocks installed in the pavement, with 4 new cold mains pipes coming into the building feeding the shop and the 3 flats. The water board would probably also have to upgrade the size of the pipe from the new stop-cocks to the MAIN in the street too, as that will probably be lead, and probably won’t give enough of a flow through to all 4 properties.
If you’re suffering from low water pressure, it might worth taking a look at where your plumbing comes into the building, you could have a little surprise just like this one waiting for you 🙂