25mm or 32mm MDPE mains pipe

[Corrado]

Hello all,

I am upgrading our house mains supply from a 15mm lead pipe to an MDPE pipe.

Thames Water charge a fortune to upgrade the pipe but it is no more expensive if you go for a 32mm over a 25mm.

I did tell my builders who are running the new 25mm pipe inside the house that I wanted a 32mm MDPE, but they seem to have delivered a 25mm coil instead!

What I am aiming to acheive is sustained water flow when more taps are turned on in the house. For example, as a downstairs tap is turned on, I want a shower to funtion with minimal loss in flow rate.

My understanding is that the 32mm pipe would be better for this, is that right?

 

[Softus]

Not really enough data to give a conclusive answer, since in practise it depends on the pressure available from the mains in your area, and other restrictions to flow that may exist within your house, but in principle you would be better of with the larger gauge pipe.

 

[chrishutt]

You will certainly get less pressure loss with the larger pipe, but it's only likely to be significant with high flow rates, low static pressure and/or long run of supply pipe. Unless you have more than one bathroom and mains pressure hot water from an unvented cylinder, 25mm should be fine.

 

[Corrado]

Hi

We actually have 2 bathrooms running of the mains, so my thinking is that 32mm would be better.

It would not hurt would it, surely it would either be the same if not better?

 

[chrishutt]

The only disadvantage is the higher cost of 32mm fittings compared to 25mm, so unless you're on a very tight budget go for 32mm.

 

[htgeng]

The only disadvantage is the higher cost of 32mm fittings compared to 25mm, so unless you're on a very tight budget go for 32mm.

Personally, a few extra quid on something as important as infrastructure to a house is money well spent. Of course if tradesmen have quoted a price they are more inclined to buy products that do the job, rather than exceed the specification for no additional gain.