I'm about to have a new water supply pipe laid which is about 1 Kilometre in length (about 5/8ths of a mile). The mains are on higher land than our property, so flow will be predominantly downhill. The contractor has suggested a 32mm bore but I am now worrying that this may be too big and 25mm might be better and put less pressure on the faucets (outlets/taps) in the house and garden. Any advice please?