See “ultrafiltration”.

(UF) A low pressure (200-700 kPa, 20-100 psi) membrane filtration process which separates solutes in the 20 to 1000 angstrom (up to 0.1 micron) size range.

Water with a specific resistance higher than 1 megohm-cm.

Water meeting USP quality requirements that has been purified by distillation, ion exchange or other suitable process from water complying with US EPA drinking water regulations, and contains no added substances.