How much waste water is there with a RO/DI unit?

[jackaninny]

Anyone know how many gallons of waste are produced per gallon a RO/DI with a typical setup? Do people just send it down the drain or do anything else with it? Can you do anything with the waste water off an RO/DI setup?

 

Thanks.

[jeffblly]

I was wondering the same thing and have found the answers to be anywhere from 1:1 waste water to pure water ratio to 3:1 waste water to pure water. I have also seen the waste water being used for laundry or watering the plants.

[neanderthalman]

in the winter, i send mine down the drain. In the summer, I redirect it to a rain barrel outside and throw it on the lawn.

 

As jeffbilly mentioned, I've also seen it used for laundry, and it was actually a neat idea. The guy I saw doing it was filling his jugs right on top of the washer, and he stuck the wastewater hose down inside. The result was two-fold. The first is that he collected the wastewater for laundry. The second was that any overflow from the jug would also drain directly into the washer and not on the floor. Smart idea, IMO.

[AZDesertRat]

The typical waste ratio is 4:1. This can vary though as most units are supplied with a non adjustable flow restrictor which is often wasting much more than necessary, especially in winter months.

Some vendors such as Spectrapure and Buckeye Field Supply ship their units with a capillary tube flow restrictor that you trim or adjust for your exact water conditions so you maintain the correct 4:1 waste ratio and is much more accurate.

Spectrapure ia also the only Manufacturer that makes a ultra low waste 1:1 waste ratio RO/DI system which uses a microprocessor to monitor and control the unit then flushes with stored DI water for the ultimate water saving system that will work in almost any water conditions. My tap water TDS is over 800 and I use one myself! There are a few others on the market which promote themselves as water saving but they generally have a short membrame life in waters over maybe 200 TDS since the concentrated brine levels are so high surrounding the membrane. It takes the DI to extract that TDS and Spectrapure is the only who has perfected that.

http://www.spectrapure.com/email/customer-...eciation.html#1

[mike30g]

could you drink or use the waste water for a fw tank? since it is going through the system wouldnt the waste water still be cleaner than the tap water? or would the remaining polutints be to high to ingest or to use in a fw tank?

i was going to be asking a similar ? like this, being i am going to be putting in a system my self. my plan is to have culligan put in the ro system since i but my drinking water from wally world and am getting my sw and ro/di from a lfs. witch all to gether is running me around 50-60 bucks a month total. the ro system from culligan is 20 bucks a month and they replace the filters when needed at no charge.

 

sorry to highjack

[AZDesertRat]

The brine or waste water is not really suitable for drinking since it contains the concentrated TDS removed from the treated water. The TDS of the waste will be 20 to 25% higher than the tap water was to begin with.

Yes it has been through a prefilter and carbon but those do little treatment, they are there mainly to protect the RO membrane which is the workhorse.

 

I would reconsider the Culligan system. Its fine for drinking water but is not an RO/DI and does not make reef quality water. At a minimum you would need to add a DI filter to it and not knowing the quality of the permeate or RO water the DI may or may not last long, only a TDS meter will tell. Plus the Culligan type systems are not usually 75 GPD so you may be doing a lot of waiting around while the systems drip, drip, drips to fill a bucket.

For $150 you could have your own reef quality RO/DI and for about $250 you could have it with a drinking water kit too. Both would include the full size refillable DI filter, a TDS meter and pressure gauge and make at least 75 GPD with the right conditions. I wouldn't pay $20 a month for straight RO when you can have the system paid for free and clear in a year or less and filter changes are very inexpensive and only required every 6 months or so.