Recently a Business Marketing Student suggested using carwash waste wash water and running it thru and RO Reverse Osmosis unit and then using it water the landscaping at the car wash and even to flush the toilet. In fact the brainchild of this concept, Paula Chavis tells an online think tank of all the details of the concept.

In critique of this invention and Paula's "real world" based marketing and sales program, I must say that although there are now many manufacturers who claim to have a completely closed-loop [recycle and reuse] system to treat water. Many of the companies who sell this equipment are not as good at marketing their products, as they should be.

In fact, my self having previously been in the cleaning industry prior before my retirement I can say that many of the systems out there are expensive, problematic and maintenance problems. Many do use RO Reverse Osmosis Units as the last step of filtration, this is because RO can offer relatively good spot-free water and is cheaper to produce than that of De-ionized water even though De-ionized water works better but costs much more.

Another issue in this invention is that in RO units it often takes 2-3 gallons to produce one gallon of RO "clean spot free water". Another important fact is that the RO units cannot handle water, which is too brackish without severely killing the life of the membranes in the RO unit. Which is the most expensive part. Nevertheless you are correct in choosing an RO system as the major component of your waste wash water recycling system. Here are some interesting articles for your further research;

1. http://www.ezinearticles.com/?Reverse-Osmosis-and-Deionized-Water-Filtration&id=41789
2. http://ezinearticles.com/?Water-Filtration-Choice-for-Mobile-Car-Washes-and-Detailing&id=41785
3. http://ezinearticles.com/?Water-Softener-Use-In-Mobile-Auto-Detailing&id=41562
4. http://ezinearticles.com/?De-ionized-Water-Strategies-for-Mobile-Car-Washes-and-Detailers&id=41564
5. http://ezinearticles.com/?Water-Purification-Manual-for-Mobile-Auto-Detailing&id=48095