Most utilities provide householders with potable water at a minimum pressure of 1 Bar (10 metres head).
This permits water-using devices to be positioned on upper stories of domestic premises.
What if the delivery pressure were only 0.2 Bar ? Water mains could be less strongly
constructed, and there would be less leakage as the stress on seals and joints would be that much lower,
How does the water get to the upper floors of houses ?
Answer: renewable energy.
Water enters the property from the mains into a covered holding cistern regulated by a conventional ballcock.
Renewable energy (solar, wind, exercise bicycle, hamster wheel, Stirling cycle engine) then pumps water up to a header tank at the top of the building, where it is then distributed by conventional pipework to the remainder of the property.
The choice of energy source is the householder's, augmented by an electrical pump at times of high demand when renewable energy is insufficient but with a large enough roof tank to act as an accumulator, not much boosting would be needed..