We have an in-ground swimming pool that has a set-up where it collects all of the water from the roof of the house when it rains. No swimming! LOL That is our 'cistern' and all of our animals get their water from that. Then our greenhouse was built over the pool. There is a cover over the pool and we do aerate the water on occasion with a free-flow form to keep oxygen levels up. It's clean and doesn't seem to hurt the animals. When the pool gets low because of no rain, then we slowly fill it from our well. We have a system of water lines and sumps that go to all of our pastures so no matter where we put the animals, we have access to water. Works out pretty darned good!