What is this clean water you speak of? Surely your horses missed the memo that the water trough HAS to have dirt in it for it to be drinkable..
Fun fact - When I bought Nikki I had to put goldfish in the water trough..Yes, goldfish.. Talk about a finicky horse, she has to have it just her way to drink..Has to have her own water bucket at shows or it's unacceptable.
Ponds?? Like sitting, misquito, bacteria infested, fish poop water?? Would you want to drink that and expect to stay healthy?