NSF/ANSI 58-2022: Reverse Osmosis for Drinking Water

Reverse osmosis water treatment plant for drinking water adhering to NSF/ANSI 58-2022 requirements.

1 in 3 people around the world do not have access to safely managed drinking water, free from contamination and available when needed. One way to purify drinking water so that it is safe for the public to drink is via Reverse Osmosis (RO) systems. NSF/ANSI 58-2022: Reverse Osmosis Drinking Water Treatment Systems specifies requirements for materials, design and construction, and performance of RO drinking water treatment systems.

What Is Reverse Osmosis?

Reverse Osmosis (RO) is a water purification technology that is used to remove a large majority of contaminants from water. The process involves demineralizing or deionizing water via pushing it under pressure through a semi-permeable Reverse Osmosis Membrane (synthetic lining). The membrane filters out unwanted molecules and large particulars such as contaminants and sediments like chlorine, salt, and dirt from drinking water. Besides removing contaminants and sediments, RO also removes microorganisms such as Shigella, Escherichia coli, Vibrio, and Salmonella that are harmful to digest as they can infect any part of the body. Essentially, RO gets water purified down to a molecular level, leaving only pure H2O behind.

To learn more about the standard (NSF/ANSI 61) for minimizing contaminants in drinking water, check out NSF/ANSI 61-2022: Drinking Water System Components – Health Effects.

The NSF/ANSI 58-2022 Standard for Reverse Osmosis System

NSF/ANSI 58-2022 addresses requirements for the point-of-use (POU) Reverse Osmosis (RO) drinking water treatment systems. These water treatment systems are used for the reduction of specific substances that may be present in public or private drinking water that should be microbiologically safe and of known quality after undergoing RO. Systems covered by this standard are intended for reduction of total dissolved solids (TDS) and other contaminants specified herein. Additionally, NSF/ANSI 58-2022 also specifies minimum product literature requirements that manufacturers must provide to authorized representatives and owners. Minimum service-related obligations for manufacturers to extend to system owners are also specified in this standard.

Water contact materials in drinking water treatment units listed under NSF/ANSI 42, NSF/ANSI 44, NSF/ANSI 53, NSF/ANSI 55, NSF/ANSI 58, and NSF/ANSI 62 are tested and evaluated under a separate protocol from NSF/ANSI/CAN 61 with criteria that were developed specifically for the intended end-use. NSF/ANSI/CAN 61 should not be additionally required for acceptance of these listed units for water contact application.

Is Reverse Osmosis Or Distilled Water Better to Drink?

Both reverse osmosis (RO) and distilled water are commonly used purification methods. They are alike in their ability to eliminate contaminants from water and their environmental advantage over bottled water, but there are substantial differences between these methods:

  1. Filtering water: RO systems remove these contaminants by passing them through a series of filters, while distillers boil the water and cool down the resulting steam to a liquid state.
  2. Re-mineralization: RO systems are commonly equipped with re-mineralization filters as the final stage of the filtration process. This means RO adds vital minerals into drinking water making it healthy for consumptions and improving the taste of water. Distillation also purifies water but does not add healthy minerals to the water, leaving tasteless water without healthy nutrients.
  3. Efficiency: Distillation does not eliminate volatile chemicals like chloramines as effectively as RO. Distilled water is only a short-term water purification solution, while reverse osmosis offers a long-term and very effective solution to get purified water
  4. Use: For residential purposes, only RO is a practical choice. RO comes with a faucet attachment that can output water from a storage tank whenever needed and in extreme cases, it can be used for whole-house filtration. This allows households to use RO water for applications such as cooking, washing dishes, and drinking. Distillers, only output enough water to be used for consumption. Residential water distillers do exist but use a lot of energy and are much less common than RO filters.

Check out NSF/ANSI Drinking Water Treatment Standards to better understand the NSF/ANSI series for water purification and treatment.

NSF/ANSI 58-2022: Reverse Osmosis Drinking Water Treatment Systems is available on the ANSI Webstore.

NSF Drinking Water Treatment Units Complete Set

NSF Drinking Water Treatment Units Set

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