With many pharmaceutical processes requiring large volumes of water, it is critical that any pharmaceutical-grade water used is protected from particulate or microorganism contamination, in order to ensure that process operations do not become inadvertently contaminated. Several approaches can be used to ensure that water remains free from contamination, including the storage of purified water or WFI (Water For Injection) at a minimum temperature of 80°C to discourage microbial growth in the storage system. Another approach is to add ozone, which acts as an antimicrobial and oxidizing agent, to ambient or hot water storage and distribution systems. Usually, water is stored in tanks fitted with a sterilizing-grade vent filter to ensure that the tank can be properly vented for filling and emptying, without the risk of contamination from the environment.

This paper discusses key considerations for selecting a vent filter for hot or ambient water tanks that are subjected to ozonation. It also provides case study data in terms of temperature, ozone concentration, exposure time and changeout frequency, helping filter users to determine their usage strategy.