I'm sorry.....but I can't help myself.
Maybe the cows just insist on the "Swiss Quality" locally sourced water!
On a more serious note, many animals are sensitive to water changes. I used to travel widely to dog agility and obedience trials in the US and we always packed water with us. Our dogs also liked certain brands of widely available bottled water-- they were so spoiled! Some local water they did not like, but of course, we didn't either.