Tom, I wouldn't change a thing if your customers (both internal and external) are happy with your cleaning results. If you do decide you need deionized water, you should consider some pretreatment of the water supply. A D.I. column will have to be regenerated sooner with any increase in water hardness. The only way to properly determine the pretreatment requirements would be to have you water supply tested by a local professional. On our saponified inline aqueous and batch aqueous cleaners, we pretreat our water by dechlorination, softening, and then reverse osmosis prior to the D.I. columns. This level of pretreatment will GREATLY increase the useful life of your D.I. columns. Steve McBride Frontier Electronic Systems (405) 624 5281 ______________________________ Reply Separator _________________________________ Subject: [TECHNET] City water or DI Author: PC:[log in to unmask] at INTERNET