NSF Protocol P231-2003

Microbiological Water Purifiers

Summary

NSF P231 evaluates water purifiers and water filters for the effectiveness to purify water to eliminate microbiological contaminants – bacteria, viruses, and live cysts.  It establishes the minimum requirements for the health and sanitation characteristics of microbiological water purifiers. This protocol is based on the recommendations of the U.S. Environmental Protection Agency’s Task Force Report, Guide Standard and Protocol for Testing Microbiological Water Purifiers (1987) (Annex B).  It is among the highest levels of certified water protection, often sought out by organizations such as military bases, schools, restaurants, and food processing plants. The protocol addresses systems having a flow rate of 5 gallons per minute (gpm) or less and contains minimum requirements for materials, design and construction, and performance of these systems. The systems are not intended to convert wastewater or raw sewage into drinking water.

Typical Test Substances

• Microbiological water purifiers and water filters (having a flow rate of 5 gpm or less)

Outline of Test Procedure

• Inoculate microorganism (bacteria, viruses, or cysts) into model water 
• Treat with test product 
• Hold for exposure (contact) time
• Add neutralizer (if necessary)
• Plating and Counting (quantitative assay)

Regulatory Agencies / Purpose

• U.S. Environmental Protection Agency (EPA)
• Other agencies 
• R&D and Marketing

Similar Methods

• NSF P248
• OECD 170
• U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers (1987) 
• U.S. EPA 810.2600 – Disinfectants and Sanitizers for Use in Water (March 2013)