save the world single handedly... well no, but looking for responsible use of RO waste water

[Magnum Man]

so since I installed an RO unit for my aquariums, gallons of waste water have been going down my drain... what could this water be used for??? I actually have 2 RO units... there is already one in the house for drinking water
Normal RO waste water is just "very hard"??? rinsing the accumulated minerals out of the RO membrane??? I'm assuming mine is currently going to have a high salt content, as my RO unit (s) are fed with water from a whole house softener... but if I could draw off my well water ( pre whole house softener ) could that water be used for rift lake tanks, or some similar use??? even with the salt ions, that I assume are in my RO waste water, could that water be used for brackish aquariums... maybe I could use it for my Tilapia aquaculture set up, or without the salt ions maybe for plants???

just seems wasteful, to run all that water down the drain... I don't think the salt residue is good for my septic system either???

 

[FranciscoB]

It is very wasteful. Much of the world, including much of the USA has been and will continue to be in a water availability crisis.
If one must do RO or RODI, two guidelines that are almost always good recommendations are 1) don't run the RO from the "softened" water line, but from the raw water line (after mechanical filration), and 2) have a pre-planned use for the "waste" water from RO.

 

[Colin_T]

If the hard water (before it gets to the house) is clean and free of harmful chemicals, I would drink that because the minerals help strengthen our bones. However, if the water has toxic stuff in, then don't drink it until it has gone through the r/o unit.

I agree with using the r/o unit on the water before it goes through the ion exchange unit.

Depending on what the pH, GH & KH of the waste water and the water before it's filtered, you could use it for Rift Lake cichlids or the Tilapia.
Lake Malawi has a GH around 300ppm and a pH around 7.6-8.0.
Lake Tanganyika had a GH around 400ppm and a pH around 8.5.

In Australia we use r/o waste water to water the lawn or garden.