@ChrisMayLA6 the purpose of Thames water (and most the other firms) isn't to manage the supply of water and treat sewage.

Their purpose is to produce as big a return as possible to investors*, the water network is just an asset they can use for that. So they can borrow massively against it (knowing the gvmt won't let it completely crumble but won't intervene due to ideology), cut maintenance, etc.
(*All overseas, wouldn't care if they caused a cholera outbreak, doing very well out of it)