In article ,
wrote:
A lot of the water supply is gravity. Sewage tends to need pumping,
if only to get it from the buried pipes to the surface treatment
works.

People who still have a loft tank may become popular with those who
have modernised and rely on direct mains pressure.

Most have 'modernised' because that was easiest for their plumber.

--
*What do little birdies see when they get knocked unconscious? *

Dave Plowman London SW
To e-mail, change noise into sound.