NSF/ANSI Drinking Water Treatment Standards

Shadow casting over glass of water resulting from NSF/ANSI standards from the treatment of their components.

Water is, of course, the liquid molecule that we need to sustain life. Any kind of contaminant in water can be detrimental to granting this basic need, as it can deter people from drinking it and even be harmful to consume.

Numerous standards published by NSF International, an ANSI-accredited standards developing organization, focus on guidelines for drinking water treatment and components, helping to assure the safe and reliable treatment and delivery of potable water. These include:

NSF/ANSI 42-2021: Drinking Water Treatment Units – Aesthetic Effects

This American National Standard establishes guidelines for the materials, design and construction, and performance of point-of-use (POU) and point-of-entry (POE) filtration systems designed to reduce specific aesthetic-related contaminants in public or private drinking water supplies. Aesthetic contaminants are those that are non-health-related, including chlorine, taste, odor, and particulates.

NSF/ANSI 44-2021: Residential Cation Exchange Water Softeners

This American National Standard establishes minimum requirements for materials, design and construction, and performance of residential cation exchange water softeners. The manual, auto-initiated, and demand-initiated regeneration (DIR) residential cation exchange water softeners addressed by this document are designed for the reduction of substances in drinking water.

NSF/ANSI 53-2021: Drinking Water Treatment Units – Health Effects

This American National Standard sets minimum guidelines for point-of-use and point-of-entry drinking water systems designed to reduce specific health-related contaminants in public or private water supplies, covering their materials, design and construction, and performance. It is intended to help reduce microbiological, chemical, or particulate substances that may be present in public or private drinking water and are considered health hazards.

You can learn more about this standard in our post NSF/ANSI 53-2021: Drinking Water Treatment Units, Health Effects.

NSF/ANSI 55-2021: Ultraviolet Microbiological Water Treatment Systems

This American National Standard fulfills a unique need among the other documents in this list. While federal, state, and local objectives provide safe water supplies without user treatment, users can still be faced with contaminants of aesthetic and health concern in their water supplies. Therefore, this standard establishes guidelines for the reduction of microorganisms using ultraviolet radiation (UV) water treatment systems, covering Class A and Class B systems for inactivating or removing different bacteria. The success of microbiological flora reduction is dependent on the intensity of the UV treatment.

Learn more about this standard and its recent changes in our post Ultraviolet (UV) Water Treatment Systems, NSF/ANSI 55-2021.

NSF/ANSI 58-2021: Reverse Osmosis Drinking Water Treatment Systems

This American National Standard sets minimum requirements for materials, design and construction, and performance of reverse osmosis (RO) drinking water treatment systems. Systems covered by this standard are intended for reduction of total dissolved solids (TDS), and they may be chemical or particulate in nature.

NSF/ANSI 60-2021: Drinking water treatment chemicals – Health Effects

This American National Standard sets health effects criteria for numerous water treatment chemicals that are added directly to water and are intended to be present in the finished water. Water treatment chemicals covered include corrosion and scale inhibitors, coagulants, disinfection and oxidation chemicals, pH adjustment and softening chemicals, and well drilling aids. Most governmental agencies in North America require compliance with NSF/ANSI 60 for water treatment chemical products.

Read more about this standard in our post NSF/ANSI 60-2021: Drinking Water Chemicals Health Effects.

NSF/ANSI 61-2021: Drinking Water System Components – Health Effects

This American National Standard sets health effects criteria for water system components—specifically the materials or products that come into contact with drinking water, drinking water treatment chemical, or both and can potentially impart chemical contaminants and impurities. System components covered include protective barrier materials (cements, paints, coatings), joining and sealing materials (gaskets, adhesives, lubricants), mechanical devices (water meters, valves), pipes, plumbing devices, and process media. Most governmental agencies in North America require compliance with NSF/ANSI 61 for water treatment and distribution products.

Read more about this standard in our post NSF/ANSI 61-2021: Drinking Water System Components – Health Effects.

NSF/ANSI 62-2021: Drinking Water Distillation Systems

This American National Standard establishes the materials, design and construction, and performance guidelines for POU/POE drinking water distillation systems and the components that comprise these systems. Distillation systems heat water to a boiling point and then collect the water vapor as it condenses. This reduces specific chemical contaminants from potable drinking water supplies as they are left behind during the process, but other contaminants can turn into gases and carry over with the water vapor. Distillation systems can also reduce microbiological contaminants.

NSF/ANSI 177-2019: Shower Filtration Systems – Aesthetic Effects

This American National Standard deals with shower filtration systems. Its requirements, in addition to product literature and labeling requirements, address substance reduction performance, materials safety, and design, construction, and structural performance.

NSF/ANSI 244-2021: Supplemental Microbiological Water Treatment Systems – Filtration

This American National Standard focuses on POU and POE mechanical filtration systems that are designed to be used for the supplemental microbial control of specific organisms that may occasionally be present in public of private drinking water because of intermittent incursions.

NSF/ANSI 372-2022: Drinking Water System Components – Lead Content

This American National Standard establishes procedures for determining lead content in drinking water system components. These requirements help users meet the Safe Water Drinking Act definition of “lead free,” or “not containing more than 0.2 percent lead when used with respect to solder and flux” and “not more than a weighted average of 0.25 percent lead when used with respect to the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures.”

Read more about this standard in our post “Lead Free” Drinking Water: Regulations and NSF/ANSI 372.

NSF/ANSI 401-2021: Drinking Water Treatment Units – Emerging Compounds/Incidental Contaminants

Systems covered under this American National Standard are intended to reduce substances that are at very low, yet measurable concentrations, but not at definitive concentrations of known health concern. The document establishes minimum requirements for materials, design and construction, and performance of drinking water treatment systems that are designed to reduce specific emerging compounds / incidental contaminants in public or private water supplies. This can include pharmaceutical, personal care products, and endocrine disrupting compounds.

NSF/ANSI/CAN 600-2021: Toxicology Review and Evaluation Procedures

This American National Standard details the toxicological review and evaluation procedures for substances imparted to drinking water through contact with drinking water system components and additives. As a companion document to NSF/ANSI 60 and NSF/ANSI 61, it is given as complimentary copy when purchasing either of those standards.

You can learn more about this standard in our post Companion Standard to NSF/ANSI 61 & 60 for Drinking Water.

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