Why water for pharmaceutical use is always kept in close loop in continuous circulation?

Water is very important & essential medium for any pharmaceutical preparation. So this use very carefully.

      Water is a best medium for most microorganisms, microorganism can be a highly pathogenic which causes serious diseases(many diseases are  water born), these pathogens infect after consumption of contaminated water, microorganisms tend to settle on a surface if water is allowed to stand in a stagnant position for few hours, these settled microorganism form a film over the surface of vessel and piping, such film formed by microorganisms is also called as bio-film, bio-films are very difficult of remove, once a bio-film is formed at a particular point then that point may form a bio-film again even after cleaning very easily as seed from this point is may not completely get removed effectively.

   Bio-films then can become a source of microbial contamination's, therefore purified water after collection in a distribution system is always kept in a closed loop in a continuous circulation.

      A continuous circulation is also not enough at some points, therefore it is aided with high temperature range from 65 °C to 80°C, a minimum temperature of 65 °C is considered a self sanitizing, but better assurance is obtained with a temperature of 80°C.

      Purified water collected should be stored in a stainless still vessel which must facilitate distribution to the point of use in a closed loop of continuous circulation, tank should be made of corrosion free material of construction, and must facilitate sanitization and easy cleaning. Thank's