RO Units

[ssdefinity]

Today I visited my LFS with the intent of buying a RO unit but I had second thoughts after the salesperson told me that it takes approx. 4 gallons of input water to make 1 gallon of purified water. Is this true?? Does anyone do anything with the "wasted water" or does that just go back down the drain? Just wanted to hear some opinions before I shell out $150-200 bucks.

[surgeon67]

Depends on the model, but that's about right (mine's 3-1). The other water goes down the drain. It contains all the rejected material from the RO membrane. It's gotta go somewhere!

I suppose if you wanted you could collect it and water plants or something with it.Top off your swimming pool maybe :lol:

What amazed me was looking at what was in the wastewater. I have a TDS meter that shows my tap water to have a reading of 122ppm on tap water, 12 on RO, and 0-1 in DI water. The waste has over 160ppm dissolved stuff.

[ssdefinity]

When you say ppm what is it measuring?

[surgeon67]

TDS=total dissolved solids.... basically everything from chlorine/fluoride to lead and copper.
ppm = parts per million