I don't know how Geoffs son pulls that off.
When I had my shop in London back in london had no water supply,not lavatory, but I had let the flat above,so paid water rates for that.Water authority tried to claim water rates from me,at a commercial rate of course. I showed the man around the premises to prove and he went away but they came back with a reduced bill for rainwater run off with the argument
that rain falls on my roof and goes into their drains. The counter argument that I had already paid that via the flat above they ignored. I gave up arguing and closed the business,which was on the cards anyway. Its just another tax, they would tax us for air if they could. Pluck 'em.