If the house has a pump feed it doesn't matter what size gov water pipe feeding the tank, the tank outlet is what matters, it is feeding the pump, I have 1" pipe from the bottom of the tank feeding the pump and 1" from there on until it branches in different directions feeding the taps, showers etc....
Also plumbed in is a bi-pass, in case one has a pump/electricity problem.
At my place, the gov water pressure will not get upstairs.
I have a 250w non-pressure tank pump, good pressure upstairs......????