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NSF/ANSI 61: The Basics

Most products that come in contact with potable water are tested under NSF 61 with the pH 5, pH 8 and pH 10 exposure waters defined in the standard. These exposure waters were designed to simulate the wide variety of potable water chemistries encountered across North America. However, these exposure waters were not designed to predict leaching of materials caused by aggressive chemicals.


To address this concern, NSF created a more extensive standard and certification. As a leader in the chemical storage tank industry, Poly Processing holds this more stringent chemical system certification and to make sure we provide the safest tank systems for drinking water safety, we certified the complete system from tank to bolt washers to this strict standard.

Each component of a public water treatment system is subjected to meeting certain criteria. The most important standard may be the NSF/ANSI 61 certification. However, there's some confusion as to what it is and what it covers.

Let's look at NSF/ANSI 61 and detail how to ensure chemical storage tanks meet the proper requirements.

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NSF/ANSI 61 is a set of nationally-recognized standards. Developed by the American National Standards Institute (ANSI) and the National Sanitation Foundation (NSF), this standard refers to water treatment requirements. Potable water equipment or products that support its production fall under this standard's jurisdiction.

Everything from ambient temperature water at various pH levels to more dangerous chemicals can be tested. In all cases, the liquid is tested before and after exposure to a given piece of equipment to determine whether anything has been leached out or extracted from the equipment.

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How to Tell if Your Chemical System Meets NSF 61

There are various levels of certification that a system can achieve. This is because NSF-61 can apply to so many different concentrations of chemicals. This variance can make understanding a specific certification challenging.

This means some manufacturers incorrectly explain certification levels for their products. Some customers may end up buying the wrong product for their application. In fact, some products listed as NSF-61 certified may only apply to potable water and not chemical storage or vice versa. 

In the next article, we will clarify the difference between the two certifications (chemical and potable water) and discuss the systems approach that Poly Processing Company takes with NSF-61 certification.

Many manufacturers are only testing pH 5, pH 8, and pH 10 exposure waters at ambient temperature, which is for potable water storage only. What they fail to account for is potential leaching of materials in chemical storage tanks. 

We recommend visiting the NSF website to ensure a product meets the standards based on the chemical application and that the certification is for the specific chemical and not for potable water storage. Verify components listed by manufacturer, along with the name of the chemical and its percentage concentration. A less-than symbol means that a tank is certified to store up to that level of concentration. 

A full system certification includes even small parts. Smaller parts like gaskets and fittings must also pass certification to consider the full system certified. It's important that all materials meet this standard for potable water and chemical storage.

Poly Processing Offers a Smart Solution

Among chemical tank manufacturers, Poly Processing is the only one with a complete chemical storage tank system that is NSF/ANSI 61 certified. Currently, we have NSF 61 Certification for 38 of the most popular water treatment chemicals on our XLPE tank systems. Additionally, our certifications cover XLPE tanks with our innovative OR-1000™ System. This system is designed and engineered to extend the useful life of a tank storing oxidizing chemicals, such as sodium hypochlorite or sulfuric acid.

In the next NSF/ANSI 61 article, we’ll look at the differences between NSF 61 chemical certification and NSF 61 potable water certification. We will discuss the testing that takes place and how you can be sure your tank system is completely certified to the right standard for its intended use.

To find out more about NSF-61, download your copy of our NSF/ANSI 61 Certification eBook.

Download the NSF/ANSI 61 Decoded eBook

Topics: Certifications and Standards