Poor Pressure on Allotment water supply

[renishawphil]

We have a water on our allotments with MDPE pipe which is 22mm.
The supply runs slightly down hill from the supply. At the bottom of the supply the pressure is pretty decent, at the top end near the supply the pressure is useless and has got worse over time.
When a tap is on at the bottom of the supply you would think the water is off.
Supply is turned on fully on etc.

Can anyone suggest what might be causing this? as we are at a complete loss as what to do and being an allotment funds are fairly tight

 

[stardanny]

Is the water supply metered?
If yes, with the outlet tap off, does the meter run?

You possible have a leak somewhere underground

Daniel

 

[renishawphil]

Yes it's metered, no leak as the meter doesn't run. There are about 5 outlet taps, the further you go away from the supply the better the pressure!

 

[dilalio]

Get the supplier out to check the pressure and flow rate at the meter is what they are supposed to supply you with. If it is then the meter/main stopcock may be defective.

 

[renishawphil]

Get the supplier out to check the pressure and flow rate at the meter is what they are supposed to supply you with. If it is then the meter/main stopcock may be defective.

Thanks got an appointment with them to come and check, i just dont understand why the pressure is pretty much ok right at the end of the supply,but near the supply its rubbish

 

[dilalio]

Because you are getting a 'head' of water in the downhill pipe run due to gravity

 

[renishawphil]

Because you are getting a 'head' of water in the downhill pipe run due to gravity

Thanks that makes perfect sense, the allotments water meter is about 5 meters from the road so they have to do some proper investigation on their own pipework, don't think we will be needing much water next week though........

 

[Agile]

What is the height difference between the supply and the lowest tap?

Do you know the difference between pressure and flow?

 

[renishawphil]

What is the height difference between the supply and the lowest tap?

Do you know the difference between pressure and flow?

I wasn't sure but I checked and now I do
The height difference is about 2.5 meters

 

[Agile]

That is only a very small difference.

Whilst it will contribute to your apparent problem it is unlikely that it will be the underlying cause.

From what you have described I don't know exactly what your problem really is.

But perhaps you don't realise that you will only be able to take water from JUST ONE tap at a time???

Tony

 

[renishawphil]

I wonder if anyone can offer any further advice here.

We have had a new boundary box on the road put in as the old one had been tarmaced over by the council. When they put this new boundary box in they said pressure was fine there.

So next thing we had done was had the meter replaced this morning (which is down hill from the boundary box). Amey Engineer said the pressure was good(he thought old meter was blocked but it wasnt)

We have a tap which is about half a meter from the the meter and is the first tap. With no other taps on you put this tap on and you get instant pressure, as if its all fine. After about 10 seconds the pressure then drops to a trickle and i mean a trickle. There are no leaks at all.

Now what could be causing this?, could it be an airlock further down the road?.

We are thinking we may need to replace the lead(or copper pipe) which runs from the boundary box to the meter.

This is most confusing and we do not know what to do next. I think the fact the tap right next to the meter is also bad is most strange (this tap is the bottom of the slope)

 

[Agile]

Did you not show the problem to the engineer?

But you need to understand that pressure and flow are not the same thing!

Tony

 

[renishawphil]

Did you not show the problem to the engineer?

But you need to understand that pressure and flow are not the same thing!

Tony

Thanks, I know pressure and flow are not the same, the engineer that came out today was just to replace the meter itself,

I am thinking the only thing to do now is replace the pipe between the boundary box and the meter, with a bigger pipe (i think 25mm , pretty sure its copper there)

 

[Agile]

Merely replacing pipe will not be likely to solve the problem.

It needs to be identified and the appropriate action taken.

But to start that you need to measure the static pressure and the flow rate from different outlets!

For outdoor supplies blue MDPE is best.

Tony

 

[dilalio]

You should get a flow measure at the suppliers stop cock... They should have done both a pressure and a flow check at that point - before you begin investigating problems your side of the meter!