Question:
Who knows of a good home water purification system and how much should it cost?

Answer: I have a reverse osmosis system that produces a little over 2 gallons a day. It cost around $700 including installation. I love it. It was well worth the cost. There are 2 filters beside the reverse osmosis membrane. The filters have to be replaced once a year (about $30 for both). The membrane is supposed to last several years. I've had mine 4 years and haven't had to replace it yet.