You could harvest rainwater.
In Scotland maybe, but in England this past summer, no chance.
You can ameliorate the situation if you have enough storage. Especially on the west side of the country and Wales of course.
A guy down here in Bristol had 5000 litres of storage which at 350 litres a day gives about 3 weeks on a 4/5 day week if there was no rain whatsoever.
He lived in a semi and got half of his neighbour's water by removing a downpipe! 
I just wonder whether the cost of tanks and pumps and general unsightliness is worth it.
Firstly Malc, how are you doing since your operation?
I just think of the lengths Thimble Brimble (Jeff Brimble) went to harvesting rain water, and he lives/lived in Wales. I can remember one post where he was up in the middle of the night disposing of the first water run-off from a gutter, before catching the remaining run-off. I can remember posting a link to an Australian website selling an automatic diverter that sent the first portion of water to the drain before diverting the rest to the water storage tank.
Years back, I monitored how much rain we got on the north-east coast during the summer with a rain gauge. It just wasn't enough, although winter rainful was much better.
There was a poster on one of the forums working in the Netherlands. I seem to remember he managed using 2 or 3 x 1000 litre IBC tanks collecting rain water from his house roof.
