Product water specifications for CEDI technologies are typically in the range of 10-16 megohm-cm with removal of weakly dissociated species such as silica and boron in the 90- 98 per cent range. This is sufficient for many industrial uses, including water production in the pharmaceutical and power generation markets. However, this quality is not sufficient for use in the microelectronics industry which requires greater than 18 megohm-cm, with most species non- detectable. In this case, and in many applications where there is a stringent silica requirement, CEDI is followed by ion exchange polishing.