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The Essential Guide to NSF 50 for Pool & Spa Sanitizing Products

In times of uncertainty, we all look for sources we can trust. We also look for unhealthy snacks, binging TV shows and too much online shopping. But looking for certainty is a lot healthier.

In the pool and spa industry, one of the most important sources of trust happens through product testing and certification. These third-party moderated processes ensure products and systems installed by pool professionals are safe, effective and built to agreed-upon standards.

When it comes to products designed to sanitize and disinfect pool water, this can be especially critical. We are talking about the health and safety of swimmers! By seeking out products certified to meet specific germicidal requirements, you can be confident you have the healthiest pools possible.

One of the most well-known certification bodies for pool and spa products is NSF International (formerly the National Sanitation Foundation). NSF can certify products not just for the pool industry, but also for a wide array of professional and consumer products.

To get the maximum value from locating NSF certified products, it’s important to have a good understanding of how that process works.

Who is NSF?

NSF is a global organization of “microbiologists, toxicologists, chemists, engineers, and environmental and public health professionals.” This team of people creates public health and safety standards while testing and certifying products according to those standards. They partner with other groups like the American National Standards Institute (ANSI) to develop standards and safeguard their integrity. 

They are a non-profit organization, originally founded in 1944. So yeah, they’ve been at it for a while. And don’t confuse it with the National Science Foundation.

Products awarded the NSF mark are widely recognized. In recent CMP surveys, 80% of professionals indicated third-party certification as the #1 factor when comparing products. And over 80% state they are willing to pay more for a product that has been certified. Suffice it to stay, NSF Certification carries weight in the pool and spa industry.

There are other organizations that test and certify products, like UL and ETL. But they do not also develop and maintain the actual standards. NSF tests and certifies products in addition to developing the actual standards. Each role is complementary but serves different purposes. These other organizations will actually certify products to the standards that have been developed by NSF. It goes without saying that the influence and importance of NSF is far-reaching.

What is “NSF 50?”

All that being said, what bearing does NSF have on the pool & spa industry? All of the relevant standards are contained in NSF Standard 50. NSF has standards that apply to Automotive, Building Products, Consumers, COVID-19, Food Safety, Lab Equipment, Nutritional, Water/Wastewater and more. But NSF 50 is the one that matters for pools and spas. 

The complete name of the standard is actually NSF/ANSI/CAN 50-2019 The standard was developed in cooperation with ANSI and is both an American National Standard and a National Standard of Canada. NSF 50 is referenced in most state codes and is an integral part of the Model Aquatic Health Code (MAHC), the International Swimming Pool & Spa Code (ISPSC) and the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC). So again – it carries a lot of weight.

You can read what ANSI has to say about the standard and its history here: https://blog.ansi.org/2020/04/nsf-ansi-50-2019-equipment-chemicals-pools


What is the difference between a code and a standard? Codes, like the MAHC or even local building codes, state what must be done in the area they are adopted. According to NSF, “A code tells you what you need to do, a standard tells you how to do it.”

Here is one of the most important things you need to remember about NSF 50. It is not one single standard. It actually defines multiple standards. Don’t miss this! If a manufacturer claims a product is “NSF Certified” then your next question should be “Certified to which standard?”  

The standards in NSF 50 range from Automation, to Water Testing, to Spray Fittings and more. And of course, sanitizers. 

Even sanitizers are divided into specific standards to fit the product. Certifications related to sanitizer products include standards for Ozone, UV and Water Conditioners. And there are new related standards currently in various stages of development or approval. 

We can break it down even further. Each standard in NSF 50 has a detailed list of requirements for the products to meet. These requirements outline details related to safety, maintenance, product instructions, durability and more. Any product with the NSF mark has likely gone through an intense series of rigorous requirements. 

Considering the time, cost and effort needed to meet these requirements, you can bet a product with the NSF mark meets a higher standard. When it comes to sanitizer products, the steps above are in addition to the testing required for disinfection efficacy.

Understanding NSF 50 Sanitizer Standards

Time to get to the point! What are the requirements for sanitizers as defined by NSF? In a nutshell, the big difference comes down to this: what does the manufacturer claim the product is doing to the water?

Ozone and UV can be tested following NSF/ANSI 50 Annex H to a Level 1 or Level 2 certification. There are specific requirements outlined for both system types.

– Level 2 certification (Supplemental) shows a 3-log kill of test bacteria.

– Level 1 certification (Secondary) shows a 3-log kill of test bacteria AND cryptosporidium. Secondary is an MAHC requirement for any high risk pool environments.

Supplemental and Secondary both still require an approved residual sanitizer – typically chlorine – to be in the water. No system is certified to operate as the only sanitizer with zero chlorine. That doesn’t exist.

What is a 3-log kill rate? 

3-log = 99.9%. If you count the decimal places, that is where we get the “3.” A kill rate can also be 2-log (99%) or 4-log (99.99%).

There are also standards for UV, ozone or AOP products that do not require verification of microbial kill rates. These standards serve other purposes. There is nothing wrong with these certifications, it’s just important to understand what they are claiming.

– Water conditioner: This certification shows a system has an effect on the water without adding any actual chemical component. A common application would be for UV systems certified to reduce chloramines.

– Gas injection: This is a functional and operational standard with no bearing on sanitization or effects to the water condition. https://info.nsf.org/Certified/Pools/14530.pdf 

Just because a product is designed to sanitize and has an NSF mark does not mean you can assume the mark is related to its sanitizing properties.
Remember: you need to understand what a system has been tested and verified to do. 

This is the difference between a system you can trust to keep the pool safe for swimmers and one that may not do what you expect. Again, any of these standards serve a purpose. They let a professional or consumer feel confident the product meets the claims set in the standard. 

That begs the question: with so many options, how do you know what specific certifications a product has?


How to verify NSF/ANSI 50 product claims.

The good news is, NSF makes it very easy to quickly research products tested and certified by NSF. They maintain a database for all products with the NSF mark. It is free to search and use. You can verify anyone’s certifications at https://info.nsf.org/Certified/Pools/. Here’s the page for CMP (listed as Custom Molded Products): https://info.nsf.org/Certified/Pools/Listings.asp?Company=0K080&Standard=050 

If a system is tested to NSF/ANSI 50 requirements by UL or ETL, you may have to contact the manufacturer to get details on their specific claims, testing and certification. Be sure to ask for data specifically related to their certification, not other independent testing that may have been completed. Other testing is nice, but if it was not part of the certification process it is not relevant to any product markings.

What CMP products are certified to NSF/ANSI 50?

Glad you asked! Here are the products currently made by CMP certified to this standard.

– DEL Ozone ProCertified as “Ozone Process Equipment.” Tested to Level 1 Secondary Sanitizer for 3-log kill of influent bacteria and Cryptosporidium. (These are the ONLY ozone systems for pools & spas to meet the Secondary Sanitizer standard.)

– AOP 25/40, DEL AOP Pro: CCS Certified as “Combination Equipment” (Ozone + UV). Tested to Level 2 Supplemental Sanitizer for 3-log kill of influent bacteria.

– AOP UV-C Pro: Certified as “Ultraviolet Light Process Equipment.” Tested to Level 2 Supplemental Sanitizer for 3-log kill of influent bacteria.

– Powerclean Salt Ultra: Certified as “In-Line Electrolytic Chlorinator Process Equipment.” Tested for maximum daily chlorine output levels.

– Ozone Contact Tanks: Tanks comply with materials and structural integrity requirements.

– Hydroseal Diverter Valves & Check Valves: Tested for hydrostatic pressure, cyclic pressure, burst pressure, head loss curve and differential leakage. (All CMP NSF Listed valves are black.)

OK that was a lot of info, what do I do now?

Here’s a quick summary of what you need to remember:

✔️ NSF/ANSI/CAN 50-2019 defines many rigorous requirements that pool products can meet voluntarily.

✔️ Because there are so many different ways to certify a product, it’s worth taking the time to look up a certification before you install it on a pool.

✔️ You can look up products with NSF for free. It’s quick and easy.

✔️ If a product manufacturer makes specific claims related to sanitizing or disinfection, you can look up their NSF Listing to see if their markings were actually tested for sanitizing properties.

One of the most important things about maintaining a pool is to keep the water clean, safe and healthy. Let’s face it: the natural state of water is to be teeming with life and bacteria. Great for nature, but not great for a backyard pool or spa! Using the right products to keep the water clean and clear is key. By looking for products that are verified and tested to meet exacting requirements, you can ensure you and your customers have the best solution for their backyard.

Pool owners want the cleanest, healthiest pool possible and they want it now. Pool pros want an easy-to-install system their customers are willing to pay for that works. We give you Next Gen AOP™.

Complete the form below to learn more about Next Generation DEL AOP and other 3rd party certified sanitizers made by CMP.



Find all available residential pool sanitizers at c-m-p.com.

For high-end or commercial water, CMP has a complete line of DEL Pro sanitizers, including the only Secondary Sanitizer certified Ozone systems. Visit cmpcommercial.com to learn more.

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