We purchased it from a pressuring salesman. Don't let them come to your house before you have time to think about what you want!!! Granted it is our mistake for making a quick decision, but water filters aren't something that everyone knows about. We are now out $4000+ and are stuck with a system that I really don't see any benefit from. If I had it to do all over again, I would just buy something to purify the drinking water. Instead we have something that purifies water in the whole house...including the toilet.