I recommend the EcoWater ECO-550 reverse osmosis system. It is a 5-stage system that is rated for 50 gallons per day. You won't use 50 gallons per day, but it won't REALLY produce that much either, since they are rated for ideal conditions. The 5 stage design really does a good job on the water... each filter takes a certain percentage of contaminants out of the water (90 -95%) so the more filters the better. You want one sediment filter and the rest carbon. You should have to change them once per year, except for the first pre-filter.