Residential Drinking Water Treatment Standards

  • Overview
  • Filtration
  • Ultraviolet (UV)
  • Reverse Osmosis (RO)
  • Water Softeners
  • Distillation Systems
  • Shower Filters

NSF developed its first drinking water treatment standard in 1973. Today, we test to seven point-of-use/point-of-entry (POU/POE) drinking water treatment standards and have certified thousands of systems and components.

The NSF POU/POE standards address the wide array of drinking water treatment technologies on the market today, including adsorptive medias, ion exchange, reverse osmosis, ceramic filters, pleated filters, ultraviolet (UV), distillation, reduction-oxidation (redox), shower filters and more.

Each NSF standard sets thorough health requirements and performance criteria for specific types of products. Contaminant reduction claims can be certified under each standard and can vary according to each water treatment technology capability. Systems that utilize more than one treatment technology may be certified under multiple standards.

Filtration

Three NSF standards cover filtration systems: NSF/ANSI 42, NSF/ANSI 53 and NSF/ANSI 401.

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

NSF/ANSI 42 establishes the minimum requirements for the certification of POU/POE filtration systems designed to reduce specific aesthetic or non-health-related contaminants (chlorine, taste, odor and particulates) that may be present in public or private drinking water.

The scope of NSF/ANSI 42 includes material safety, structural integrity and aesthetic, non-health-related contaminant reduction performance claims. The most common technology addressed by this standard is carbon filtration.

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

NSF/ANSI 53 establishes the minimum requirements for the certification of POU/POE filtration systems designed to reduce specific health-related contaminants, such as Cryptosporidium, Giardia, lead, volatile organic chemicals (VOCs) and MTBE (methyl tertiary-butyl ether), that may be present in public or private drinking water.

The scope of NSF/ANSI 53 includes material safety, structural integrity and health-related contaminant reduction performance claims. The most common technology addressed by this standard is carbon filtration.

NSF/ANSI 401: Emerging Compounds/Incidental Contaminants

NSF/ANSI 401 addresses the ability of a water treatment device to remove up to 15 individual contaminants (listed below), which have been identified in published studies as occurring in drinking water. While not a public health issue, the contaminants covered in NSF/ANSI 401 have been detected in drinking water supplies at trace levels and can affect some consumers’ perception of drinking water quality. (NSF/ANSI 401 also applies to reverse osmosis (RO) water treatment.)

Pharmaceutical Drugs

  • Meprobamate: a compound found in anti-anxiety drugs.
  • Phenytoin: an anti-epileptic drug.
  • Atenolol: a beta blocker drug.
  • Carbamazepine: an anti-convulsant and mood-stabilizing drug.
  • Trimethoprim: an antibiotic medication.
  • Estrone: a prescription birth control drug.

Over-the-Counter Medications

  • Ibuprofen: an over-the-counter pain reliever and anti-inflammatory medication.
  • Naproxen: an over-the-counter pain reliever and anti-inflammatory medication.
  • Herbicides and Pesticides
  • DEET (N,N-Diethyl-meta-toluamide): a pesticide and common active ingredient in insect repellents.
  • Metolachlor: an organic compound that is widely used as an herbicide.
  • Linuron: an herbicide often used in the control of grasses and weeds.

Chemical Compounds

  • TCEP (tris(2-carboxyethyl)phosphine): a chemical compound used as a flame retardant, plasticizer and viscosity regulator in various types of polymers including polyurethanes, polyester resins and polyacrylates.
  • TCPP (Tris(1,3-dichloro-2-propyl)phosphate): a chemical compound used as a flame retardant.
  • BPA (Bisphenol A): a chemical compound used as a plasticizer.
  • Nonyl phenol: a collection of compounds often used as a precursor to commercial detergents.

Ultraviolet (UV)

NSF/ANSI 55: Ultraviolet Microbiological Water Treatment Systems

NSF/ANSI 55 establishes the minimum requirements for the certification of point-of-use/point-of-entry (POU/POE) ultraviolet (UV) systems and includes two optional classifications:

Class A systems (40 mJ/cm2) are designed to disinfect and/or remove microorganisms, including bacteria and viruses, from contaminated water to a safe level. Class A systems may claim to disinfect water that may be contaminated with pathogenic bacteria, viruses, Cryptosporidium or Giardia.

Class B systems (16 mJ/cm2) are designed for supplemental bactericidal treatment of public or other drinking water that has been deemed acceptable by a local health agency. Class B systems may claim to reduce normally occurring nuisance microorganisms.

Reverse Osmosis (RO)

NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems

NSF/ANSI 58 establishes the minimum requirements for the certification of point-of-use (POU) reverse osmosis systems designed to reduce contaminants that may be present in public or private drinking water.

The scope of NSF/ANSI 58 includes material safety, structural integrity, total dissolved solids (TDS) reduction and other optional contaminant reduction claims. The most common optional claims addressed by NSF/ANSI 58 include cyst reduction, hexavalent and trivalent chromium reduction, arsenic reduction, nitrate/nitrite reduction, and cadmium and lead reduction.

NSF/ANSI 401: Emerging Compounds/Incidental Contaminants

NSF/ANSI 401 addresses the ability of a water treatment device to remove up to 15 individual contaminants (listed below), which have been identified in published studies as occurring in drinking water. While not a public health issue, the contaminants covered in NSF/ANSI 401 have been detected in drinking water supplies at trace levels and can affect some consumers’ perception of drinking water quality.

Pharmaceutical Drugs

  • Meprobamate: a compound found in anti-anxiety drugs.
  • Phenytoin: an anti-epileptic drug.
  • Atenolol: a beta blocker drug.
  • Carbamazepine: an anti-convulsant and mood-stabilizing drug.
  • Trimethoprim: an antibiotic medication.
  • Estrone: a prescription birth control drug.

Over-the-Counter Medications

  • Ibuprofen: an over-the-counter pain reliever and anti-inflammatory medication.
  • Naproxen: an over-the-counter pain reliever and anti-inflammatory medication.
  • Herbicides and Pesticides
  • DEET (N,N-Diethyl-meta-toluamide): a pesticide and common active ingredient in insect repellents.
  • Metolachlor: an organic compound that is widely used as an herbicide.
  • Linuron: an herbicide often used in the control of grasses and weeds.

Chemical Compounds

  • TCEP (tris(2-carboxyethyl)phosphine): a chemical compound used as a flame retardant, plasticizer and viscosity regulator in various types of polymers including polyurethanes, polyester resins and polyacrylates.
  • TCPP (Tris(1,3-dichloro-2-propyl)phosphate): a chemical compound used as a flame retardant.
  • BPA (Bisphenol A): a chemical compound used as a plasticizer.
  • Nonyl phenol: a collection of compounds often used as a precursor to commercial detergents.

Water Softeners

NSF/ANSI 44: Cation Exchange Water Softeners

NSF/ANSI 44 establishes the minimum requirements for the certification of residential cation exchange water softeners designed to reduce hardness from public or private water supplies.

The scope of NSF/ANSI 44 includes material safety, structural integrity, accuracy of the brine system and the reduction of hardness and specific contaminants from a known quality water source. The most common claims addressed by NSF/ANSI 44 are barium reduction, radium 226/228 reduction and softener performance.

Distillation Systems

NSF/ANSI 62: Drinking Water Distillation Systems

NSF/ANSI 62 establishes the minimum requirements for the certification of POU/POE distillation systems in terms of material safety, structural integrity, total dissolved solids (TDS) reduction and a product literature review.

Standard 62 also covers contaminant reduction claims including total arsenic, chromium, mercury, nitrate/nitrite and microorganisms from public and private water supplies.

Shower Filters

NSF/ANSI 177: Shower Filtration Systems – Aesthetic Effects

NSF/ANSI 177 was developed to cover the safety and performance of shower filtration products. Certification to NSF/ANSI 177 confirms your product’s material safety, structural integrity, minimum flow performance and its ability to reduce free available chlorine.

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