NSF/ANSI 42-2019: Drinking Water Treatment for Aesthetics

A nice, clean class of drinking water with a NSF/ANSI 42-2019 aesthetic.

Picture a glass of water. Odds are it shares a striking similarity with the one above. We like our water a certain way, especially the type we need to drink. Setting aside the variance in appearance, odor, etc. in whatever form it takes to occupy 71% of the earth’s surface and an indeterminate amount of the cosmos—water likely arrived on our planet via comets and asteroids—we want this dipolar transparent liquid to be pleasant. Appearance is important for the substance that we literally drink for survival.

Aesthetics extends beyond water’s appearance. In fact, the systems covered by NSF/ANSI 42-2019: Drinking Water Treatment Units – Aesthetic Effects not only reduce substances affecting the aesthetic quality of water (impurities such as chlorine and taste/odor), but can also add chemicals for scale control or limit microbial growth in the system.

The treatment systems addressed by NSF/ANSI 42-2019, which can be either point-of-use (under-the-sink, water pitcher) or point-of-entry (whole house), are designed to reduce specific substances that may be present in public or private drinking water considered to be microbiologically safe and of known quality.

The standard establishes minimum requirements for materials, design and construction, and performance of drinking water systems dealing with aesthetic (nonhealth) effects contaminants in water supplies. This includes gas chromatography/mass spectroscopy (GC/MS) analysis, structural integrity, and test methods for bacteriological performance. It also specifies minimum product literature and labeling information for a manufacturer to supply to authorized representatives and system owners.

NSF/ANSI 42-2019 revises the 2018 edition of the same American National Standard for filters that limit the aesthetic effects of drinking water treatment units. In keeping the document current, this revision clarifies testing for pH in the sampling procedures for chloramine reduction testing, and it corrects a previous error in Table 5.1 for “Structural integrity testing requirements.” All Annexes in NSF/ANSI 42-2019 were changed from alpha characters to numeric, and are now preceded by “Normative” or “Informative.” For example, the previous Annex A is now known as Informative Annex 1 (I-1).

For guidance on drinking water treatment units that reduce health-related contaminants, please refer to NSF/ANSI 53-2018: Drinking Water Treatment Units – Health Effects.

NSF/ANSI 42-2019: Drinking Water Treatment Units – Aesthetic Effects is available on the ANSI Webstore.

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