HELP - New water pipe 25mm or 32mm best flow and pressure

3 Oct 2020
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United Kingdom
Hi all,

Currently have 20mm MDPE pipe coming into the property and thames water main to the outside TW stop cock is lead. Im getting 2.5 bar pressure and only 14l/min. there is another stop cock on my property from the thameswater stop cock which is also piped lead and from stop cock to water meter (in the property) is 20mm MDPE blue pipe. I am hoping to fit a megaflow but have been told by plumber need to upgrade pipe to 32mm, before I do this and pay lots of money moling wanted to check...

1. Can i get rid of my stop cock to improve pressure and flow?
2. will upgrading the small lead pipe from stop cock to stop cock make much difference?
3. the water meter in the house is over 20 years old and only has 22mm in/out can this be upgraded?
4. is the only option to run a new pipe to get the desired pressure and flow despite the thames water lead pipe only being 3/4inch

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You need to have your water main checked at the boundary to see what the mains can actually deliver first before going down the road of replacing anything at a serious cost.
I would also ask your plumber to be onsite when they do the test as I recently had that issue with Scottish Water (rare occurrence as they are usually spot on). They came out and performed a test and stated that the main would deliver up to 4 bar @29L/Min. I asked to see the result as I didn't see him actually use anything to do the test and then the chap got a bit flustered and suggested that the equipment had been disconnected. I insisted and it seemed he didn't actually have the correct test equipment with him and he had just been guesstimating after 'looking' at the flow at the mains.
Turns out when the proper test was performed the main was only capable of supplying 2.5 bar @ 21L/Min dynamic!
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Im getting 2.5 bar pressure and only 14l/min

As above, get it checked at the boundary. If it is 2.5 bar there as well you won't increase it by re-piping with a larger diameter pipework.
Hi guys, yes the TM chap did the test at the boundary and showed me pressure at 2 bar and flow 30l/min at the garden tap I measured and it is at 2 bar 13l/m?
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i guess will going 32 mm future proof it for when they eventually change the lead on their end?
also will just removing my stop cock and fitting a wider pipes to meter help?

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