RO/DI Water waste ?

So, i'm looking into a RO/DI System for my father-in-laws tank... He's concerned about the amount of waste water that the system we're looking at puts out. Are there more efficient systems out there or are you pretty much guaranteed to have a system that has a at least a 1-2 gallon ratio of waste water to purified?

here's the system i've been looking at...

AQUARIUM REEF RO DI REVERSE OSMOSIS FILTRATION SYSTEM - eBay (item 200463962352 end time Apr-24-10 12:58:36 PDT)

 

it depends on how much u are willing to spend

 

even the higher end ones i've see have a 1 to 1 ratio. for me i get 1 good gallon out of 4!! so yours sounds pretty good to me!

 

spectapure or something like that.. 1 to 1 "so ive heard"

 

holy fudge that's expensive... are there any other systems out there with a 1/1 or 1/2 ratio under 500?

 

Not that work for any length of time. Membranes must be flushed and Spectrapure uses a microprocessor and stored DI water to do that which is how they lower the 4:1 waste ratio to 1:1 or less. Others attempt to flush using tap water but it has the very same TDS you are tring to eliminate and concentrated to boot so does not flush well at low ratios. It has been tried for years and years and just does not last long. With a normal 4:1 waste ratio your brine or waste is only 20-25% higher than tap so flushes OK.
Membranes only flush while you are making water so while it seems like a lot consider how much water you plan to make in a months time. If you make 20 gallons you only flush 80. You send much more than that down the toilet every day.

 

was wondering when you'd see this post ... yeah, i think i'll just try to talk him into one of the more economically friendly versions and maybe try catching some of the waste water for use in say the garden or something... There's no harmful stuff in the waste water i assume? I'm not sure i'd personally want to drink it but i'd think it'd be fine for watering the plants/vegtables ect.

 

Its fine for most uses. At 4:1 waste ratio the brine or waste TDS will be 20-25% higher tha the tap wate rwas to begin with since you are concentrating the TDS from that 1 treated gallon into the 4 waste gallons so it carries it away from the membrane.
You can water the lawn or landscape, wash the car although it may spot, put it in a pool or pond ...