I have never used tap water and I do not trust the water from down here, so getting r/o system just makes more sense on the other hand I was told that it needed to have a di unit as well is that correct ? is it really useful to get a tds meter , i have never tested the r/o water compared to tap but i do noticed that if the water is from another r/o system or filters are old there seems to be some algae growth, and Ray my wife wanted that system to in our home but our plumber stated it was to late during the building of the home to go back and install it supposedly!!!1