A bloke can stick up a water tank and collect the stuff when it falls on the roof. For free.
Alf refers, of course, to water.
It’s something he prefers to avoid, although he does consume his share of it in his tea and coffee. And some of his mates put a drop of it into their whisky.
If you don’t get it straight from the skies and into a water tank, which is true for most people nowadays, you can turn a tap and it will flow into a jug, your kitchen sink or the bath.
This being so it has seemed odd to Alf that anyone would want to buy their water in a plastic bottle from the supermarket, then have to hump it home.
But it takes all sorts, eh?
And when there are customers bursting to buy their water in plastic bottles at a supermarket, there will will be someone willing to supply it.