NSF/ANSI National Standards have been developed to establish minimum requirements for the safety and performance of these products. The standards and protocols are explained in detail below.
- NSF/ANSI 42: Drinking Water Treatment Units – Aesthetic Effects – establishes minimum requirements for materials, design, construction, and performance of drinking water systems dealing with aesthetic effects contaminants in water supplies. It also specifies minimum product literature and labeling information for a manufacturer to supply to authorized representatives and system owners. These types of filters are certified to reduce aesthetic impurities (not health-related) such as chlorine and taste/odor in microbiologically safe water. These can be point-of-use (under the sink, water pitcher, etc.) or point-of-entry (whole house) treatment systems.
- NSF/ANSI 44: Residential water softeners – establishes the minimum requirements for certification of residential water softeners using a cation exchange resin that is regenerated with sodium or potassium chloride, reducing hardness from public or private water supplies. The scope of NSF/ANSI 44 includes:
- Reduction of hardness and specific contaminants from a known quality source
- Material safety
- Structural integrity
- Pressure drop
- NSF/ANSI 44 Technical Requirements
- Softening capacity and rinse effectiveness
- Accuracy of brine system
- Accuracy of information provided to end users
- Elective claims may include Barium reduction, Radium 226/228 reduction, Efficiency of salt and water consumption.
- NSF/ANSI 53: Drinking Water Treatment Units – Health Effects – 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. Certified filters address a contaminant with a health effect. Health effects are set in this standard as regulated by the U.S. Environmental Protection Agency (EPA) and Health Canada. This standard offers over 50 contaminant reduction claims. Some of the most popular include lead, Cryptosporidium, VOCs and chromium..
- NSF/ANSI 55: Ultraviolet Disinfection Systems – establishes guidelines for the reduction of microorganisms using ultraviolet radiation (UV) water treatment systems. The success of microbiological flora reduction is dependent on the intensity of the UV treatment. UV treatment systems inactivate or kill bacteria, viruses and cysts in contaminated water (Class A systems) or to reduce the number of non-pathogenic bacteria in disinfected drinking water (Class B).
- NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems – 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). RO systems incorporate a process that forces water through a semi-permeable membrane. Most reverse osmosis systems incorporate one or more additional filters on either side of the membrane. It was developed by a joint committee with equal representation from regulators, manufacturers and end users. This standard includes requirements addressing various aspects of these systems, including:
- Safety of materials in contact with drinking water
- Structural integrity
- TDS (total dissolved solids) reduction performance
- Efficiency rating
- Recovery rating
- Contaminant reduction performance
- Relevant information for the end user
- NSF/ANSI 60: Drinking Water Treatment Chemicals – Health Effects – establishes the minimum health-effects requirements for the chemicals, chemical contaminants and impurities that are directly added to drinking water from drinking water treatment chemicals. This standard does not establish performance or taste and odor requirements for drinking water treatment chemicals.
- Chemicals within the scope of this standard include but aren’t limited to:
- Corrosion and scale inhibitors
- Coagulants and flocculants
- Disinfection and oxidation chemicals
- Well-drilling aids
- pH adjustment, softening, precipitation and sequestering chemicals
- All other specialty chemicals used in drinking water treatment
- NSF/ANSI 61: Drinking Water System Components – Health Effects – establishes minimum health-effects requirements for the chemical contaminants and impurities that are indirectly imparted to drinking water from products, components and materials used in drinking water systems. This standard does not establish performance, taste and odor, or microbial growth support requirements for drinking water system products, components or materials. NSF/ANSI 61 is intended to cover specific materials or products that come into contact with drinking water, drinking water treatment chemicals or both. The products and materials covered by the scope of this standard include but aren’t limited to:
- Protective barrier materials (cements, paints, coatings)
- Joining and sealing materials (gaskets, adhesives, lubricants)
- Mechanical devices, including treatment products (water meters, valves, filters)
- Pipes and related products (pipes, hoses, fittings)
- Plumbing devices (faucets, drinking fountains)
- Process media (filter media, ion exchange resins)
- Nonmetallic potable water materials.
- NSF/ANSI 62: Drinking Water Distillation Systems – 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. Distillation systems heat water to the boiling point, and then collect the water vapor as it condenses, leaving behind contaminants such as heavy metals. Some contaminants that convert readily into gases, such as volatile organic chemicals, can carry over with the water vapor.
- NSF/ANSI 177: Shower Filtration Systems – Aesthetic Effects – provides guidelines on materials, design, construction, and performance. In addition to regular product literature and labeling requirements, address substance reduction performance (free chlorine only). Shower filters attach directly to the pipe just in front of the homeowner’s showerhead.
- NSF/ANSI 244: Supplemental Microbiological Water Treatment Systems – evaluates 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. The filters covered by this standard are intended for use only on public water supplies that have been treated or that are determined to be microbiologically safe. These filters are only intended for protection against intermittent microbiological contamination of otherwise safe drinking water. For example, prior to the issuance of a boil water advisory, you can be assured that your filtration system is protecting you from intermittent microbiological contamination. The standard also includes material safety and structural integrity, similar to other NSF/ANSI drinking water treatment unit standards. Manufacturers can claim bacteria, viruses and cysts reduction for their filtration system.
- NSF/ANSI 372-2022: Drinking Water System Components – Lead Content – 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.”
- NSF/ANSI 401: Drinking Water Treatment Units – Emerging Compounds/Incidental Contaminants. 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. Treatment systems for emerging contaminants include both point-of-use and point-of-entry systems that have been verified to reduce one or more of 15 emerging contaminants from drinking water. These emerging contaminants can be pharmaceuticals or chemicals not yet regulated by the EPA or Health Canada.
- NSF P231 – Establishes minimum requirements for materials, design and construction, and performance of drinking water treatment systems that are designed to protect from microbiological contaminants. Microbiological water purifiers are certified for health and sanitation based on the recommendations of the EPA’s Task Force Report, Guide Standard and Protocol for Testing Microbiological Water Purifiers (1987) (Annex B).
Keep in mind that certification to an NSF/ANSI standard or protocol does not mean that a filter, purifier or treatment system will reduce all possible contaminants. It’s important to verify that the filter, purifier or treatment system is certified to the applicable standard for the reduction of the contaminants of most concern to you or your family.
The following are my favorite certifying bodies (in alphabetical order):