RO/DI unit question

[SCFatz]

Ok I have this at home now:

http://www.aquariumadvice.com/viewtopic.php?t=85303

All in all I think its going to work out well.But I'm a litte lost on something.

The question is about the "drain".
The unit has six independent filters in all.The "drain water" leaves after the first four filters.Its also maybe three times (perhaps more) the volume of "finished " rodi water.

Or to put it another way...3/4 of the water going through the first four filters gets wasted to the drain.

In actuality,had I hooked it up the way the direction said from the start I would never had known how much was draining as waste.Also since it does make it through the first four filters I have to assume it is RO,just not DI yet.Seems like quite a waste.

Can anyone tell me why this would be this way?

All its going to do the way it is spend my first four filters faster because most of the water going through the filters is going to the drain.

Why would it be designed to filter water just to waste it?

I work in a chemical manufacturing plant so my core understanding of filteration is sound,but this really has me scratching my behind.

What am I missing?

 

[SCFatz]

I'm going to bump this once just to be sure the others here who have one (there are others i think) just to get some feed back.Has anyone who owns it ever noticed how much filtered water it wastes?

 

[austinsdad]

That much waste water sounds about right. Maybe 2 - 3 times bad water vs. good/filtered water. First time the sife realized the ratio, she flipped.

I don't know if you have the space, but I keep 3 trashcans in my laundry room. One for pre-mixed SW, a second for RO/DI water, and a third for waste water. We use that for cold and wrm water laundry and house plant waterings.

 

[seaham358]

Thats normal a 4-1 is normal on most units. its just the way they work?? Its not going to use the filters faster. Depending on your water quality you can get a year out of the Micron and Carbon filters. You Membrane should last 3 years and your resin is the media that you will need to change out. If your water is good you may get hundreds of gallons before needing to change it out. If you water is bad you may only get one or two hundred.

 

[SCFatz]

Thanks for the replies guys.Good to know its at least normal.

I think my water supply is pretty good....and we are looking around for a tds meter so we will know when it is failing but i suspect it will be a long while.

I'm still lost on why it must go through the first three filters before draining though...any thoughts on the reasoning there?