We have noticed that, with one of our piggies, Bear, that he drank an awful lot of water when he first came here, but since he's settled in he's drinking about the same as all of the others... except Boomer of course who does seem to have an OCD when it comes to his water bottle. He drinks a bottle a day and "panics" when we remove it to re-fill it. He has got a little better over the last month or two though so it could just be that some pigs take longer to settle in and see their water bottle as a bit of a "comfort thing"