Hot weather and thirsty pigs

Today has been a lovely hot day - about time as the rest of June has been pretty poor weatherwise. The Stonework on the barn is almost finished (tomorrow should see it complete) and the shuttering for the ring beam which will top the wall is well under way.
The pigs are constantly turning their water trough over which is driving me mad (refilling it is a major task). I've tried digging it into the ground and weighting it down with huge rocks but they are so strong they always manage to tip or push it over or - then they cry all afternoon because it's hot and they need a drink. I either need one of those ancient stone vessels that weighs in at several tonnes or an automatic drinker/fountain linked to a header tank somewhere the pigs can't reach it.