Filtration as part of the validation and routine testing of a purified water system

A distillation system, which includes a steam condensate supply, pre-treated before distillation by passage through carbon and mixed resin barrels, is described. Filtration of 5-litre aliquots from a storage tank/ring mains system through a 0.45-micron cellulose filter identified contaminants (rust from the ring mains and carbon from the barrel) which were not detected by the British Pharmacopoeia tests for purified water.