thirsty piglets

Another piglet conundrum - why is the water in this puddle so superior to the water trough?
I've spent this beautiful sunny day wisely - a walk at Blenheim with a friend and her toddler daughter this morning and another, evening, stroll up to the farm with a different friend. I've said before, but I do feel really lucky to have had so much friendship lavished on me while I've been recuperating and it's made me resolve to try to be as good a "friend in need" when required.