water butt empty!

It's only April and already one of the water butts is empty with another about half full. I never thought when I moved to Cumbria that I'd ever be short of water. The problem is all the potatoes that I'm growing in containers this year. Now that they've reached a good size and are, hopefully, forming nice fat tubers they need copious amount to drink. How are all you growers down south coping. Watching the forecasts I see it's even warmer where you are so things must be getting a bit dry by now.