I have an existing place that i will be knocking, and building a new house. It is currently supplied by a lead water main. It says on the affinity water web site, that if i change my water main to plastic, i can ask them to change my lead communication pipe to my boundary. So basically, i can get a lead free water supply. They say that they "normally" connect to a 25mm plastic supply. They don't however say that they won't connect to a larger pipe, (under 63mm or it needs certain tests)

So as the new house will be much larger than the existing, with 4 bathrooms, and a W.C. kitchen and utility, would you try and get them to connect to a larger pipe ? If so what size.  I'm thinking that if i could get that sorted now, it might prevent me having to pay under there development scheme.

Thanks for you responses in advance.

25mm will be fine, 32mm is the next size up and you wouldn't get bigger than this.

25mm is good and, at least in some areas, note that your standing charge will be higher if you select a larger diameter.