Advice on mains flow rate

Hi all,

Having a bit of an issue with our mains water pressure. We had a survey for a heat pump, and had a flow rate of 9L/min measured, described as "pants". Following this, we got United Utilities out who did a similar test - the pressure was "fine" (forgive me for forgetting the reading), but flow rate again measured at 9L/min. Internal stop tap was checked as fully open. Our immediate neighbour was kind enough to let the UU guy do a test on his taps, and he's getting a flow rate of 20L/min.

UU guy checked the external stop tap, which looks like a cheap plastic affair, and sadly lays in our drive and firmly within the property boundary, and so UU are "unable" to assist in diagnosing or even changing the tap.

As best I can tell, my only option here is to get someone out to rip up the drive to get deep enough to the pipes and either check or replace. However, I have no idea how this works as of course the mains pressure will still be there - would I have to coordinate with UU and get the water to the estate turned off so work can be done? Or should I just lump it and accept that we can only run one tap at a time? For example, the shower feels "adequate" but if someone downstairs forgets it's running and turns on the kitchen tap, the shower is reduced to a feeble dribble.

I'm half paranoid there could be some kind of leak between the external and internal stop taps which, if left unattended, could potentially erode away at the ground under the house.

House is a 2017 build, built by Persimmon (lol). Does anyone else know any other avenues I could go down before the drastic (and likely very, very costly) action of ripping up the drive?

I've got a crushed 15mm ground pipe that happened when I dug foundations.
This effects flow rate but pressure is ok.
Because it's copper on our estate there is a problem with stones rubbing pipe in the ground causing bursts, so some have switched to poly pipe which has increased pressure and flow massively.

2017 should be poly pipe so you should have same readings as neighbours

If the district mains is delivering 20 L/Min - as indicated by your neighbours supply - then there has to be something wrong with your side of things.
1st test would be to check that the comms pipe to the mains toby is OK, did UU do that check? maybe at the meter, if you have one? That will confirm that there is 20L/Min at that point, then it has to be from there to the house that the flow is being restricted. Bit surprising given it was only built in 2019.

Flow path is mains > outside stop tap under the drive at the front of the house > supply pipe runs entire length of house to kitchen at the back > internal stop tap under sink, meter directly after the tap, and then a straight pipe with various taps, including that for the sink and outdoor tap.

So it seems the measurement would be relatively indicative that the flow rate just after the meter is indeed 9L/min. Unless you're suggesting we could do with disconnecting the pipe directly after internal stop tap and measure there if possible? Which would then rule in or out the meter and internal piping as possible issues?

Yes - only way to really test is to start at the end and work backwards and check the supply at each different connection point to rule out any given fitting or fixture until getting to the point when the supply tests the same as the mains/neighbours.

I've taken a picture of the outdoor stop tap:


upload image


Flow is bottom (street) to top (house). The plastic housing with the hex cap reads "Hand tight plus 1/4 turn". I'm assuming this is just some kind of cap and not a flow regulator or anything to that degree. Any worth in turning off both outdoor and indoor taps and loosening that hex cap incase there's some kind of filter in there? Struggling to find any kind of identification on the tap manufacturer or model.

EDIT: Just to note the tap is as fully open as it can be, despite it not being fully inline.

Can't understand why UU couldn't test there.

jj4091 said:

Can't understand why UU couldn't test there.

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I suppose there's a change I could badger them repeatedly, however the original bloke who came out said it wasn't something they'd do as this tap is within in my property boundary, in the middle of the drive.

The blanking cap is where a water meter would screw on.
Turn off the water and have a look under the cap (open a tap to relieve pressure).
AFAIK these meter manifolds are fitted with single or double check valves on the meter outlet part.
So you might find the check valve is full of debris.
Turning on the valve (with a cloth over the meter port) might give you an indication of whether the flowrate is ok at that point.

Gasguru said:

Turning on the valve (with a cloth over the meter port) might give you an indication of whether the flowrate is ok at that point.

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What, try and guesstimate the rate of flow with a cloth over the flow? If your musing about the blanking cap is correct then possibly try and manufacture a connection to this point with a length of hose connected to it so flow can then be turned on and measured by discharge rate into a bucket

karlbbb said:

UU guy checked the external stop tap, which looks like a cheap plastic affair, and sadly lays in our drive and firmly within the property boundary, and so UU are "unable" to assist in diagnosing or even changing the tap.

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If they are saying its not their ownership/responsibility tell them you are going to take it out and ask them how they will isolate their mains feed to your property so the work can be done.

Not sure to what lengths you want to, or can go to, but you could get a spare cap here https://www.cwberry.com/mwm-pp112-water-meter-adaptor-plug and fit a test point into it.

jj4091 said:

Not sure to what lengths you want to, or can go to, but you could get a spare cap here https://www.cwberry.com/mwm-pp112-water-meter-adaptor-plug and fit a test point into it.

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Or possibly one of these with hosepipe connected https://www.screwfix.com/p/flomasta-brass-compression-adapting-male-coupler-15mm-x-3-4-/82086

It's pretty obvious to see the difference between 9 litres/min and 20 odd litres/min but surely it's not beyond anyone on here to calculate the flowrate as the boundary box fills with water.
Also be aware that some of these caps appear to restrict the flowrate so you might want to look into that too.

karlbbb said:

UU guy checked the external stop tap, which looks like a cheap plastic affair, and sadly lays in our drive and firmly within the property boundary, and so UU are "unable" to assist in diagnosing or even changing the tap.

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I think your install falls into a bit of a grey area - usually toby's are located within a boundary box out on the highway close to the property boundary and everything after that point is the supply pipe and the owners responsibility. The external toby for your supply is within the boundary so the only reason for that, I would presume, would be down to the mains location or that there was no space on the highway to locate it.

There would usually be an agreement between the owner and supplier around of all of that though and who would be responsible for what. May even be in the deeds.

I would suggest there is a discussion to be had over responsibilities here. Don't talk to the UU engineer, they'll invariably just quote the party line, talk to the head office management and escalate.

From the UU point of view there's nothing to be done...9 litres/min almost certainly complies with their minimum requirements..on my old patch 8 was deemed sufficient.