A Guide to NSF Water Filtration Certifications: Answering Commonly Asked Questions

A Guide to NSF Water Filtration Certifications: Answering Commonly Asked Questions

Posted by Kenton Jones on Jul 10th 2024

Standards make a big difference in every aspect of modern life — especially our drinking water. That's why Multipure designs and manufactures our water filters with the integrity that comes from rigorous standards and formal third-party certifications. Multipure filters focus on the fine-detail technologies of carbon filters to deliver better-tasting and more healthful water. We offer a diverse selection of products that can filter out “forever chemicals” and microplastics, bacteria, and unpleasant odors, and ultimately improve the taste. And one of the keys to it all is standards, and more specifically, NSF water treatment device standards.

Some consumers are surprised by the level of engineering that goes into water filtration, given water's deceptive simplicity, but that engineering is necessary for the exceptional filtration performance we demand for our consumers. To better serve our consumers, it is our goal to explain the essential technologies of water filtration.

Understanding NSF Water Certification

Understanding NSF water filter ratings is important to ensure you're getting safe and effective filtration products for your drinking water.

1. What Does NSF Certified Mean?

NSF is widely recognized as “The Public Health and Safety Organization.” Its purpose is to ensure that products perform as their manufacturers claim. The NSF mark can be found on the packaging of products that have been tested and certified by the organization — a differentiation sellers and buyers seek out specifically.

NSF is a not-for-profit organization that dates back to 1944. Its first project was to implement cleanliness standards for soda fountains. It started as the National Sanitation Foundation, but after expanding to test all types of products, including health, beauty, cooking, cleaning, food safety, environmental, and others, it became globally recognized as “NSF” and officially changed its name.

Its role in water filtration products goes beyond performance testing to include determining standards and performing extensive consumer education. Today, it ensures that certified filters treat what they say they will. For example, if a manufacturer claims a filter reduces bacteria, NSF tests it to make sure it does. If a filter box says it can reduce lead or arsenic, that filter is tested to make sure it delivers as promised.

2. What Are the NSF Water Filter Ratings?

The following NSF protocols are set to ensure the safety and performance of products used to treat drinking water. Certification to an NSF/ANSI standard or protocol doesn't mean a filter, drinking water system, or purifier will reduce all potential contaminants or is able to pass their robust series of tests. Verify that the water filtration system is certified to the applicable standard to reduce the contaminants of most concern to you.

  • NSF/ANSI 42: This standard includes filters certified to reduce aesthetic impurities like chlorine, taste, and odor. They may be point-of-use or point-of-entry treatment systems.
  • NSF/ANSI 44: This standard includes water softeners that use a cation exchange resin that is regenerated with potassium chloride or sodium.
  • NSF/ANSI 53: These filters are certified to reduce contaminants that cause health effects, as regulated by the U.S. Environmental Protection Agency (EPA) and Health Canada. Both standards 42 and 53 include adsorption and filtration processes, such as carbon filters.
  • NSF/ANSI 55: This standard includes systems that use ultraviolet light to kill bacteria, cysts, and viruses in contaminated water and those that reduce the amount of non-disease-causing bacteria in disinfected drinking water.
  • NSF/ANSI 58: This standard covers reverse osmosis systems that incorporate water filters and reduce contaminants regulated by the EPA and Health Canada.
  • NSF/ANSI 62: This standard includes distillation systems, which heat water to a boiling point and collect the water vapor as it condenses, leaving contaminants behind.
  • NSF/ANSI 177: These filters include those placed right in front of a showerhead to reduce free chlorine.
  • NSF/ANSI 244: The filters covered by this standard are meant only for use in public water supplies that have been treated or determined to be microbiologically safe.
  • NSF/ANSI 401: This includes treatment systems verified to reduce one or more of 15 emerging contaminants from drinking water, such as pharmaceuticals or chemicals not yet regulated by the EPA or Health Canada.
  • NSF P231: This standard covers microbiological water purifiers certified for health and sanitation based on the EPA's Task Force Report, Guide Standard and Protocol for Testing Microbiological Water Purifiers.

The Importance of NSF Certification for Water Filters

NSF standards benefit consumers because they provide basic protection and enable them to zero in on solutions to their problems. These situations range from serious health concerns to a concerning smell or odd taste. The NSF certification gives users confidence in the protection they're purchasing for their family and that the filter does what it says it will.

1. Why Do We Need Certified Water Filters?

The rigorous NSF certification process tests water filters for quality, performance, and safety. With NSF certification of a water filter or component, you can ensure the product will live up to its promises from the first drop of water to the last.

As with every other company in every industry, some water filter manufacturers are prone to making exaggerated claims about their products. Their claims about the contaminants they treat — such as arsenic, lead, or asbestos — or the life span of their systems might not match up with a consumer’s actual experience. This can be misleading.

To ensure a water filter manufacturer provides accurate information, check whether its products have been third-party certified. Independent organizations like NSF protect public health by offering standards and certifications that consumers can trust. NSF standards for water treatment systems enable customers to determine the right products for their households' specific requirements.

2. Are Carbon-Based Filtration Systems Safe?

Yes! In fact, the use of carbon to filter water dates back to ancient times. Properly formulated carbon is effective, safe, plentiful, and affordable, making it a popular choice.

Other respected authorities on healthy water — the Water Quality Association (WQA) and International Association of Plumbing and Mechanical Officials (IAPMO) — also certify carbon-based filtration systems for the effective reduction of contaminants. WQA and IAPMO also certify the activated carbon according to NSF/ANSI standards for many kinds of systems, both point-of-use and point-of-entry.

NSF Water Filter Standards

The following information addresses how NSF water filter standards are developed and what they mean, including NSF/ANSI Standard 42, 53, 401, and P231. Note that some companies will have one of their products certified yet imply that all their products have this certification. Or, they will certify for one contaminant in a category and imply that they are certified for all the contaminants. As a result, it's critical to look deeper into the exact standards each of a company's products is certified for.

1. What Does NSF/ANSI Standard 42 Certification Mean?

The NSF/ANSI Std. 42 Certification is known for its ability to remedy the aesthetic side effects of water, such as slight or strong odors from sulfur, iron, or chlorine. Water can become discolored due to minerals in it, and many people like to filter out the chlorine or chloramine used to treat public water systems. Many other factors can cause an odd taste in water that people wish to eliminate.

This type of filter would be used to reduce particulates such as sand, but it does not eliminate the types of pathogenic microorganisms that are typically present in, say, backcountry water. Carbon filters are most often used for this kind of treatment, and the certification testing for NSF 42 uses tap water.

2. How Are NSF Water Filter Standards Developed?

When a consumer sees “NSF/ANSI” followed by a number, it signifies that the product has been certified. The number corresponds to the category of filtration performance it will achieve. “ANSI” refers to the American National Standards Institute, an organization that has helped develop standards in many industries since 1918.

NSF and ANSI have many checks and balances in place to maintain objectivity and transparency. They develop the standards for filters and other drinking water products by consulting and reaching a consensus with a diverse group of members from many sectors of society:

  1. Academics
  2. Consumers
  3. Environmental associations
  4. Government entities
  5. Industry representatives
  6. Private citizens
  7. Public health officials

3. What Is NSF/ANSI Standard 53 Certification and Its Significance?

An NSF Std. 53 water filter certification is a nationally recognized minimum standard for point-of-use and point-of-entry filtration systems. The standard guarantees that with proper use, the filter may reduce certain contaminants that threaten human health, though note that the company can choose what contaminants they certify for. Many of the toxins potentially present in private and public water supplies can make us sick:

  • Arsenic
  • Cryptosporidium (a microscopic parasite)
  • Disinfection byproducts (DBPs)
  • Giardia (a single-celled microscopic parasite)
  • Lead
  • Methyl tertiary-butyl ether (MTBE)
  • Volatile organic compounds (VOCs)
  • PFOA
  • PFOS
  • Microcystin

NSF analyzes the integrity of the water treatment system in a few different ways. They examine its material safety, analyze structural integrity, and make sure the product lives up to its claims. NSF states in its description that the most common technology used for achieving this standard is carbon filtration.

Many people worry about their health and how their drinking water affects it. They want to know it’s free of “forever chemicals” and lead — especially with high-profile news stories spotlighting poor drinking water quality. City pipes get old, contamination leaks from former industrial sites, and materials get spilled. There are many ways undesirable substances reach groundwater and local drinking water supplies, but many of those events are beyond control. What people can control instead is the filter their water passes through before they drink it.

4. How Does NSF/ANSI Standard 401 Certification Work?

An NSF Std. 401 water filter certification focuses on what they classify as “emerging compounds and incidental contaminants.” This consists of a long list of constituents of growing public concern — particularly microplastics, pharmaceuticals, pesticides, and insecticides. There is a growing concern about the microplastics that are being found in our water. Microplastics come from clothing, single-use plastic bottles and many other consumer products.

A filter that has Standard 401 certification brings the carbon technology needed to reduce these potentially harmful contaminants.

Some of the medications that can make their way into our water include:

  • Atenolol (beta-blocker)
  • Bisphenol A (BPA — a compound used as a plasticizing agent)
  • Carbamazepine (an anti-convulsant and mood stabilizer)
  • Diethyl-meta-toluamide (DEET — a pesticide)
  • Estrone (birth control)
  • Ibuprofen (pain-reliever)
  • Linuron (herbicide)
  • Meprobamate (a compound in anti-anxiety drugs)
  • Metolachlor (herbicide)
  • Microplastics
  • Naproxen (a pain reliever and anti-inflammatory)
  • Nonylphenol (compounds used in commercial detergents)
  • Phenytoin (anti-epileptic)
  • Tris 1 chloro-2-propyl phosphate (TCPP — a flame-retardant compound)
  • Tris 2 chloroethyl phosphate (TCEP — a compound used in various polymers)
  • Trimethoprim (antibiotic)

5. What Is the Role of NSF/ANSI P231 Certification in Water Safety?

The NSF/ANSI Protocol P231 verifies that microbiological elements, including bacteria, viruses, live cysts and other waterborne pathogens, are treated or reduced. It meets standards set forth by NSF and the Environmental Protection Agency (EPA).

This type of water filtration is frequently used in institutional settings such as prisons, mental health facilities, and sometimes schools. It is also commonly found in places where food is handled or processed, including restaurants and commercial kitchens.

While the NSF testing standard is even more stringent than the EPA’s requirements, both entities test with and for worst-case scenarios, such as water laden with microorganisms. The filters tested and certified under NSF Protocol P231 reduce pathogens as claimed.

Beware of filters that claim to have this ability but that are not tested and independently verified. Not all manufacturers voluntarily subject their filters to the rigors of testing, but savvy buyers know about and look for the marks that signify peace of mind.

6. How Is an NSF P231-Certified Water Filter Tested?

Just as manufacturers can choose to voluntarily test their products, they can also specify the rigorousness of those tests. For example, the full field of testing for a P231 certification includes 10 days, half of which are challenges by tap water and the other half by natural water sources.

The worst-case water might contain mixtures of organic matter and dirt, all subjected to extreme temperatures. Beyond that, the certification testing includes challenging the filter at the end of its life to ensure it’s still delivering results until it reaches capacity.

Choosing the Right NSF-Certified Water Treatment System

Use the following tips to select the right NSF-certified water filtration system for your home.

1. What Are the First Steps in Selecting a Water Treatment System?

The first step to choosing the right system for your home or business is to know what's in your water and whether it is supplied by a public entity or a private well. It is fairly easy to ascertain what’s in your water:

  1. Request or review a copy of the annual water quality report: Any water supply and distribution operation should have this report on file, and most have the report available online. The report shows which additives and compounds are in the water and how much of each. You can often find this information on the company's website.
  2. Have well water tested by an independent laboratory: If you use well water, has it been tested at an independent laboratory? Water conservation districts, county land departments, private entities, and sometimes universities offer water analysis services with choices for how exhaustive you want the analysis to be.

The results of the water quality report will point you toward an appropriate choice of filter. Given how connected the global water table is, your filter choice will have to contend with a variety of potential contaminants:

  • Perfluorooctanoic acid (PFOA)
  • Perfluorooctanoic sulfonate (PFOS)
  • Microcystin
  • Microplastics
  • Asbestos
  • Arsenic
  • Chlorine
  • Dioxins
  • Lead
  • Insecticides
  • Mercury
  • Microbiological material
  • Minerals such as iron
  • Particulate matter (dirt, sand, etc.)
  • Perchlorate
  • Pesticides
  • Pharmaceuticals
  • Polychlorinated biphenyls (industrial chemicals)

While this is only a partial list of contaminants, as you do not know what happens to your water once it leaves the municipality and can travel miles to your home, water filtration is classified by the specific types of contaminants treated by the product: aesthetic, health, emerging, and microbiological. For example, if only the taste or odor of water needs improvement, that is an example of aesthetic filtering.

You will also see point-of-use (POU) and whole-house, also called point-of-entry (POE), filter options. Point-of-use includes water bottles, pitchers, and drinking water taps that are separate from the kitchen faucet. Point-of-use filters treat the water just before it's consumed, as refrigerator-mounted filters do. Whole-house filters intercept and treat the water at its entry point into a home or building before it gets used for anything.

2. What Is the Difference Between “NSF Certified” and “Certified to NSF Standards"?

"Certified to NSF standards” and “tested according to NSF standards" are phrases all too often used by companies to falsely bolster product performance claims. At a glance, this may appear to be the same as NSF-certified. After all, the product is certified to the same standards, right? Remember, though, that details matter when it comes to NSF certification.

“Certified to NSF standards” or “tested according to NSF standards” does not rule out internal, manufacturer-controlled testing, whose results cannot be guaranteed to be impartial and unbiased. Nor does it ensure that the product performance was actually tested for the entire life of the filter — some companies only test the water for a few gallons and base their performance claims on that limited data.

True NSF testing and certification involves multiple stages and criteria. For drinking water treatment systems, the main testing criteria are designed to verify that:

  • The contaminant reduction claims are true from the first to the last drop of water.
  • The housing, parts, and filter do not leach anything harmful into the water.
  • The system is structurally sound.
  • The product labeling, advertising, and literature are accurate and are not misleading.
  • The materials and production process have not changed, allowing for consistent product quality over time.

NSF certification testing does not just check the product submitted to them for testing. It goes further by conducting unannounced manufacturing inspections. In these inspections, NSF inspectors enter the manufacturing plant and remove products and literature from the manufacturing and assembly lines to ensure that the item submitted for testing is the same as the product being sold.

In addition, NSF also purchases products for sale — either in a storefront or online — again to ensure that the product sold and the included literature are in compliance and match the products and literature submitted for testing and produced at the manufacturing plant.

3. How Do I Know if My Water Filter Is NSF-Certified?

When comparing water treatment technologies and products, the most important rule is to make sure the product is NSF-certified. It is not enough to simply acknowledge the NSF certification — to ensure you are getting the best system, you need to go a step further. Why is this important? Because NSF certification provides an unbiased, independent, third-party guarantee that something performs according to its claims.

Fortunately, making sure a product is NSF-certified is easy:

  1. Check to see if the product has the NSF seal on the packaging.
  2. Go to the NSF website to double-check that the specific product by that manufacturer is currently certified and what it is certified to reduce.

Consumers can be confident that a product works as stated when it is certified by NSF, the premier independent certification organization for drinking water treatment in the world. Certification allows for an “apples-to-apples” comparison with other drinking water systems because all NSF-certified systems have undergone the same rigorous and comprehensive testing.

4. What Are Some Examples of NSF Certified Water Filters?

Multipure offers NSF-certified countertop, below-sink and inline water filter systems to provide you with clean drinking water. Our list of NSF-approved water filters includes:

  • Aquaperform: At Multipure, we offer the Aquaperform, a countertop or below-sink carbon block water filter certified NSF 42, NSF 53, and NSF 401.
  • Aqualuxe: The Multipure Aqualuxe is another carbon block water filter you can place on the counter or under the sink. This filter is certified NSF 42, NSF 53, NSF 401, and NSF P231.

Professional Partners Make a Difference

Multipure has been in business for over 50 years, offering expert knowledge of the certifications, standards, testing, review, and usage of carbon water filtration systems. We like to share that knowledge and help people make informed decisions. The decision on a drinking water filtration or treatment system can affect a family’s health and quality of life. In some settings, it can mean the difference between illness and wellness.

Multipure's water filtration systems are NSF-certified and protect consumers from various harmful contaminants. You can use our systems at home, on the go, or in the yard, accessing a safe source of drinking water wherever you go. NSF certification guarantees our products' exceptional performance — and so do our 90-day money-back guarantee and lifetime warranty.

Our countertop, below-sink, and inline systems fit in any area of the home where you need clean drinking water. Browse our line of Multipure Drinking Water Systems today, including the Aquaperform and Aqualuxe.

Don’t hesitate to contact Multipure to discuss your filtration needs. For Life. For You.