earlier comment.
My original comment was based upon something that happened just after we were married 25 years ago. The shared drain which ran thru our back garden got blocked and we and the other householders upstream (or should that be 'upshit'?) suffered the consequences of smelly gardens and a rising tide of unmentionable matter in each of the drain chambers in the back gardens. Had to be fixed and reasonably fast.
Called DynoRod to resolve the problem and got hit for a £78 bill, which in 1978 was a princes ransom given that a working mans salary was of the order £60 per week (£3000 per year). Shared amongst the affected householders but nonetheless a lot of money in those days.
PoP