Low mains water flow stumped!

Joined
4 Oct 2012
Messages
9,321
Reaction score
2,826
Location
East Renfrewshire
Country
United Kingdom
No, sometime older connecting couplers can silt up,or corrode, that can then restrict the flow. It seems the static pressure is ok but dynamic is poor.
A 1 bar dynamic drop per outlet is quite signinficant but again that could be down to a restriction somewhere. You need to know from the transporter what the dynamic readings (pressure and flow) are on the main, that gives you the starting point. The mains can alost always be considered to be dynamic as you can just about guarantee that multiple users are actively using the mains at any given time. If the readings are signig9fcantly dirfferent at your mains tap then it's almost certain that your mains supply pipe is to blame.

Where are you located? Are you rural or on the outskirts of a town?
 
Sponsored Links
Joined
26 Jun 2022
Messages
7
Reaction score
0
Country
United Kingdom
No, sometime older connecting couplers can silt up,or corrode, that can then restrict the flow. It seems the static pressure is ok but dynamic is poor.
A 1 bar dynamic drop per outlet is quite signinficant but again that could be down to a restriction somewhere. You need to know from the transporter what the dynamic readings (pressure and flow) are on the main, that gives you the starting point. The mains can alost always be considered to be dynamic as you can just about guarantee that multiple users are actively using the mains at any given time. If the readings are signig9fcantly dirfferent at your mains tap then it's almost certain that your mains supply pipe is to blame.

Where are you located? Are you rural or on the outskirts of a town?
Connecting couplers for what though? Old lead to new plastic ?
I am in the middle of a town but at a high elevation relative to the surrounding area.
 
Joined
4 Oct 2012
Messages
9,321
Reaction score
2,826
Location
East Renfrewshire
Country
United Kingdom
Connecting couplers for what though? Old lead to new plastic ?
depends what's under the ground as part of the supply pipe. we're not saying that's what it is, just what it could be.

Have you asked the neighbours as to what their supplies are like, can you ask a neighbour to do the test on theirs too and see if there's a correlation?
 
Joined
26 Jun 2022
Messages
7
Reaction score
0
Country
United Kingdom
Had the water board round and they have 3 bar of static pressure at the meter (same as what i've got internally) and over 25L flow rate. They also measured my garden tap at around 7LPM which is the same figure I came to.

Also lifted some floorboards to find the black poly pipe does exit the property as I was half expecting to find galvanised steel coming into the house and then poly connected up to that.

As it exits the house, I thought it seems unlikely that it isn't black poly all the way to the meter?

Options:
1) Start digging up garden in case it does transition to lead/steel or on the off chance I find a random stopcock or coupler.
2) Get a new 25mm mdpe supply moled in.
3) ??

The water board said poly is coming to the end of its life and lots are leaking now so seems like it's best to not b*gger around with it and go with option 2?
 

Attachments

  • IMG_20220722_173740.jpg
    IMG_20220722_173740.jpg
    473.6 KB · Views: 16
Sponsored Links
Joined
4 Oct 2012
Messages
9,321
Reaction score
2,826
Location
East Renfrewshire
Country
United Kingdom
Had the water board round and they have 3 bar of static pressure at the meter
OK, as that's measured at the mains, it will always be dynamic as the mains is always being used by lots of people all the time so that's a result

Now it's all about increasing the flow, as suggested, that needs a fatter pipe.

If option 2 is a goer then that would be the best future proofed solution. Depending on what you want the mains to feed inside the property then even consider 32mm.
 
Joined
15 May 2022
Messages
136
Reaction score
31
Location
Cork
Country
Ireland
Once that's roughly measured/estimated, the attachment might be a handy aid to navigation if pipe ID is known, the static head is known @ 3.0bar.

 
Joined
26 Jun 2022
Messages
7
Reaction score
0
Country
United Kingdom
Roughly what distance is it from the meter to the house stopcock?

Around 20m,

I used one of those calculators before the flow should be about 20LPM so somewhere there must be a large restriction.

When I moved in the stop tap by the meter had moved so it was pushed right up against the side of the pit so the tap couldn't be rotated, the water board came out and replaced it with a 1/4 turn plastic jobbie. My guess is whatever caused the stop tap to move is also crushing my pipe.
 
Joined
15 May 2022
Messages
136
Reaction score
31
Location
Cork
Country
Ireland
Around 20m,

I used one of those calculators before the flow should be about 20LPM so somewhere there must be a large restriction.

When I moved in the stop tap by the meter had moved so it was pushed right up against the side of the pit so the tap couldn't be rotated, the water board came out and replaced it with a 1/4 turn plastic jobbie. My guess is whatever caused the stop tap to move is also crushing my pipe.

I get 14.4LPM from a 3/4" bath tap at a dP of 2.65bar (3.6/0.95) measured with PG downstairs through 20M of 21mm, 11.5MM ID Hydrodare HDPE (50 year old) piping, (theoretically, per friction loss table, should only be 1.2bar), if I reduce the flowrate to your 7.75LPM I get a dP of 0.77bar, so seems something up with your piping all right if it has the same 11.5mm ID, so running a new pipe in 32MM or whatever seems the way to go.
 
Joined
4 Oct 2012
Messages
9,321
Reaction score
2,826
Location
East Renfrewshire
Country
United Kingdom
If you have low flow just now, then that is down to the supply pipe you currently have to your property, regardless of what length/dimension/restrictions/etc there may be.

Putting in a new run of 25/32mm MDPE will maximise that flow and get you close to what the mains is currently running at out at the meter, it doesn't need to be complicated.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top