Bacteria Prevention in High Purity Water System, Part 1

Maintaining a consistent level of quality is the goal of any process and high purity water system is no exception. Industries such as biopharmaceutical, electronics, manufacturers, hospitals, laboratories, power generators and many others require ultrapure or deionized water in their manufacturing and research. These high purity water systems must be exceedingly reliable in their ability to meet the quality requirements n order to sustain the production specific goals and standards. Therefore, the design and improvement of high purity water systems is a highly involved process.

High purity water applications that must comply with strict regulations can be negatively affected by the slightest increase in bacteria levels. If bacteria colonies are allowed to continue to grow, this can create significant problems. If the results of testing show that bacteria levels are found to be outside acceptable limits, it may result in the loss of weeks worth of product and significant process down time.

This can be a difficult problem to prevent because water provides an ideal environment for bacteria to develop. Also, nutrients that bacteria feed off of can form on hard surfaces of water piping systems. In addition, defects in the piping, connection points, welds, instrumentation and fittings of these systems can contribute to bacterial contamination of incoming water. Therefore it is critical to minimize the bacteria-forming sites along with nutrient levels in the water. Preventing and safeguarding against bacteria-forming sites in high purity water systems starts early on, with the design of a system. The design of the system should also include methods for dealing with sanitation.

There are many different types of water processes that must consider bacteria levels in their design. These can include pharmaceutical, semiconductor and reagent grade water systems.
For example, purified water that carries the “USP” designation can either be a product water such as water for injection (WFI), or as an ingredient in drug product production. The United States Pharmaceopia, USP, carries their own list of documents, the national formulary (USP-NF) documenting pharmaceopeial standards. Water to be used in the production of food is typically regulated by the FDA and must utilize “food-grade” equipment and instruments.

Reagent water used for analytical purposes, however, is subject to American Society for Testing and Materials (ASTM) standards. According to ASTM specifications there are three grades (A, B and C) which specifically address microbiological and endotoxin contaminants.

Water specifications related to bacteria levels from common governing bodies are listed in the specifications below.

USP 27 Pharmaceutical Grade Water

  • Endotoxin (Purified Water) –  No Specification
  • Endotoxin (WFI) –  <0.2 EU/mL
  • Bacteria (Purified Water) –  <100 cfu/mL
  • Bacteria (WFI) –  <10 cfu/100 mL
American Society for Testing & Materials (ASTM)
  • Max. Heterotrophic Bacteria Count –
  1.   Type A –  10/1000 mL
  2.   Type B –  10/100 mL
  3.   Type C – 100/10 mL
  • Endotoxin, EU/mL –
  1.   Type A –  <0.03
  2.   Type B –  0.25
  3.   Type C –  No Limit
When the proper system requirements and specifications are defined, the system design can be completed in order to minimize bacteria levels. For more information regarding bacteria prevention in high purity water systems, contact a U.S. Water representative.

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