My whole plan is to go with the RO system if I do car lots. It is 5 times cheaper then DI water. I already have a water softener but that doesn't get you a spot free rinse. You need to get your TDS at or below 40 ppm to get a spot free rinse. Right now my area's TDS is at 160 ppm. An RO system will drop the TDS ppm by 95%. I would then have a TDS of 8 ppm. I will only get an RO system if I do car lots. The total cost for the complete RO system is $6,000. I will still use a water softener for my house jobs. I can make RO water for 2 cents a gallon. That price includes filters, salt, water, electricity, depreciation of the unit (over a 5 year span), etc. For DI water it would cost 10 cents a gallon. Getting back to my original question. How many gallons per car does people use to rinse? I wanted the guys who use DI or RO water to give me a clue. If you use tap water and don't pay but $1 per 1000 gallons you aren't concerned on how much water you use but if you are a guy who pays anywhere from 2 to 10 cents per gallon for DI or RO water then you pay attention to how much water you are using. If it takes 5 gallons per car then with DI water it will cost 50 cents a car to rinse but if I get the RO I could do the same amount for 10 cents a car. You only get one chance at making a first impression. I don't want to go out there and spot the cars the first time. Using a water softener does not lower the TDS ppm of your water. You are exchanging the calcium in the water for sodium. So you might get less spotting but you will now get streaks. I have talked at lengths with these guys at the Water Treatment place (Culligan) and at the township water plant. One thing I was told is that by running a lot of RO water through a pump it will shorten the life of the pump some. If I have to replace a pump once a year because of it though that would only be $300. That is less then 3 days wages of paying a helper.
