My gov. supply is probably 40mtrs to the tank, it is less than 1", at the meter it looks like 1/2" internal plastic, in and out, could be a tad more though.
Most of my place has 1/2" pipe, it is all sunk in the walls, nothing on show.......????
Back home, we would use 1/2"/12mm copper pipe all over the place wiv no probs, though no pump was needed there....????