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To establish a database to determine whether selected chemicals, not included in the NCCLS standards, could be detected in point-of-use water treatment systems (POUs), we analyzed water samples collected from 50 POUs following service maintenance. These samples were first analyzed for compliance with NCCLS standards for reagent grade water. A spectrophotometer was then used to analyze product water samples for detectable levels of free and total Cl, ClO2, Cr, Cu, Fe, Mn, NO3, SO4 and Si. The following percentages of water systems had detectable levels chemicals (according to water type). For Type I water, free Cl was found in 89%, total Cl, 50%; ClO2, 11%; Cr, 28%; Cu, 78%; Fe, 33%; Mn, 22%; NO3, 89%, Si, 83%; and SO4, 17%. For Type II water, free Cl was found in 71 %, total Cl, 50%; ClO2, 21%; Cr, 29%; Cu, 63%; Fe, 25%; Mn, 4%; NO3, 54%; and Si, 75%.

Municipal water was purified by an electrodeionization (ED) process for use in the research and diagnostic laboratory. Except for elevated silica levels electrodeionization product water met NCCLS Type II water specifications. An extensive battery of physical, microbiologic, and chemical tests were performed to determine the effect of this technology on water quality and to demonstrate the interaction with the other components of a typical water purification system.