Drinking Water

I have a 7 stage RO unit on the house with a final stage to add helpful minerals back in (a lack of calcium and magnesium will leech it from your bones as the water tries to neutralize PH, so adding them as a final stage PH balances it). I can't see how a good RO unit is practical in an RV. A "good" under the sink mount takes up a decent amount of space and requires 40 - 60 PSI to force it through the membranes. As others have said the waste ratio is usually anywhere from 1:1 up to 5:1 on inefficient units. Adding the FW tank is a good idea until it over fills. Also I have seen units that will handle chlorinated water.