# Ro/di System Waste Water



## Jared35 (Sep 15, 2009)

Can you do freshwater changes with
the waste water from a ro/di system? What's actually left in the waste water? Also I purchased the
Kent additive for ro/di water which puts back the good things for
fish.

Thanks for the help just trying to understand


----------



## JoeDizzleMPLS (Nov 5, 2007)

The waste water is full of all the crap that your filters take out, you don't wanna use it on your tanks unless you mix it back with RO water... I use it to water plants, otherwise you can just let it go down the drain.


----------



## xeloR (Jan 2, 2009)

its amazing how much more waste you get vs filtered


----------



## CLUSTER ONE (Aug 2, 2006)

You could probably use a bit, but i wouldn't use much. if yo want to use it for something water plants with it or throw it on your lawn


----------



## jharrison (Dec 7, 2004)

I would think it would gunk up your RO/DI filters really fast, and they are pricey.


----------



## bobme (Feb 17, 2003)

If you have a ton of RO/DI water you can add more more RO filter to that and reuse your waste water.
I think a zero waste system runs 8 different RO system linked together.
but no, you cant and shouldn't ever use the waste water to fill a fresh water tank.


----------



## rchan11 (May 6, 2004)

I've been using the waste water from RO/DI for my fresh water tanks for years without any problem. Use a TDS meter to measure water quality. There's not much difference between tap water and waste water.

Here's an explanation from another site.

The RO stands for Reverse Osmosis and refers to the chemical/mechanical method of filtering the water. Basically the water is forced through a semi-permeable membrane that allows water molecules through, but blocks most other organic and inorganic materials. This can only happen with a pressure differential from one side of the membrane to another. But the membrane is very delicate and would burst if presented with the normall pressures a normal filter cartridge endures. Thus the water flows across the membrane with only a moderate differential pressure. The second reason for the waste water is that since the pores in the membrane are very small, they clog easily. The flowing water across the membrane also flushes the membrane clean. Even so, most RO units have a method of flushing the membrane with full flow to clean it further.


----------



## Grosse Gurke (Jan 3, 2003)

Pretty much what I was thinking. I used it to top off one of my tanks and havent had a problem. It has less ppm them my tap water.


----------



## CLUSTER ONE (Aug 2, 2006)

Grosse Gurke said:


> Pretty much what I was thinking. I used it to top off one of my tanks and havent had a problem. It has less ppm them my tap water.


 How can waste water have less ppm then tap water assuming you purify tap water to get ro? Like said, itf your tap water isn't that hard to begin with it could work, but if its hard water you may not want to use it. Take a tap water and waste water to a lfs or do a test your self to see how hard it is.


----------



## redbellyman21 (Jun 27, 2004)

waste water is equivalent to super brita water.. if u follow the lines, it passes threw sediment and carbon before going to waste... So I mean its carbon'd and sediment free! I wouldnt use it on my SW tanks.. but I try to use it for my freshwater tanks whenever possible to save from wasting good drinking water or plant and garden water. actual ro water is better once buffered to your style for perfection, but I never had any problems using waste water from an ro... its way way better than just tap!


----------



## Grosse Gurke (Jan 3, 2003)

sean-820 said:


> Pretty much what I was thinking. I used it to top off one of my tanks and havent had a problem. It has less ppm them my tap water.


 How can waste water have less ppm then tap water assuming you purify tap water to get ro? Like said, itf your tap water isn't that hard to begin with it could work, but if its hard water you may not want to use it. Take a tap water and waste water to a lfs or do a test your self to see how hard it is.
[/quote]
Yeah...it has already gone through 3 stages of filtration before it gets to the membrane where it is sorted between waste water and water that goes to my DI filter. I think my tap water is in the 19ppm and my waste water is around 9ppm. I havent checked the waste water since I changed all my filters....but the final product is 0ppm


----------

