Water pressure drop

[Stevie76]

Alright all-new to this and looking for some help.

I'm installing a garden building with a new 22mm mdpe water connection to exsisting main 40m from house supply.

The house water supply is 20m from utility companies water main and (still!!!) in 15mm lead.

So when plumber connected old lead supply house to new mdpe supply for garden building the house water pressure significantly reduced. It's still usable (about 6 litres per min) and I was expecting a drop with such a long feed to garden building.

Is there anything I could do to improve pressure to house? Was considering replacing old 15mm lead from the water main to the house stop cock with 22mm although not sure worth hassle for benefit gained?!?!
Also considering a booster pump but again cost/noise/space benefit to gain seems in balance.

Any help greatly appreciated.

 

[mfarrow]

What's the dynamic pressure like at the house? Ie what does it come out as with a garden tap open? Does opening another tap (e.g. kitchen) significantly decrease the flow?

With a 20mm MPDE pipe (15.4mm ID) you'll get a drop of 0.15bar at 6 l/min, see http://www.pressure-drop.com/ . To be honest, that's not a great deal, but will increase with more flow.

You need at least 0.5bar left at the bottom I would think.

Are you sure you haven't got a part-open tap or isolator valve?

 

[magicmushroom666]

It shouldn't drop pressure in the house just by adding an extra T'd off section, unless you mean reduced pressure in the house with water running in the other building?

 

[Stevie76]

Thanks for the replies. I'm a total novice but since the T was added, the water flow has reduced from approx 9 l/hr to 6 l/hr without anything else running.

Edit

I've just been in the garden and there is a straight connection of the 22mm pipe (builders decided to use 2x25m instead of 1x50m run) and appears to be a leak!!!!
That could well be the problem
Once fixed I'll update you.
Thanks again.

Yeah so it turns out the old boy fitting the straight connector f**ked it up. An hours digging thru slop, new fitting put in and hey presto water pressure back to normal.

It's a lesson learned!!!

Thanks again

 

[vinn]

OP,
The 15mm (actually 1/2") lead you refer to is, presumably, a communication pipe &, for free, some utilities will up it to a larger diameter plastic from their mains to your external stop-tap or boundary.

For the builder to use a fitting to piece in a water service pipe is well wrong - get it changed or down the road it might leak again.

The supply should be typically run in one length from external stop-tap/communication pipe to internal stop-tap.

 

[Stevie76]

Totally agree it should have been one long run. But they make connectors to connect!

Anyway-all is well (for now) and once again, I appreciate all the replies.