The one and only type that worked for us was the tyre drinker shown in Supplies for Farmers, £12.99, cat. no. S6PTB (as I have no idea how to do links). The bowl has a completely flat rim that the pigs can't get their noses under, and it sits in a deep tyre which tends to get pushed around rather than turned over, for reasons unknown. We too had a sow who could shift and turn over an enormous Belfast sink full of water, simply because there was space for her to get her snout under it to give her the necessary leverage. They always had huge, deep, filled up wallows as well, so all the weight lifting must have been just for fun, or because there was the most tempting piece of mud just under where the belfast sink was.
Loved the two photos of pigs cooling off in baths.