Which Water Filter Is Right for You?

Your tap water likely plays an essential role in your daily routines. But in many homes, drinking water from the tap contains chemical compounds that can be harmful to health. Water filtration can help reduce or remove these contaminants, ensuring your drinking water is as safe as possible for you and your family. 

“Ensuring we have clean, good-tasting water that’s free of health-related contaminants as much as possible is a huge part of staying healthy,” says Rick Andrew, water filtration expert, former NSF employee, and ROSE scientific advisory board member.

But with all the options lining store shelves, what’s the best water filter option for your home? Choosing a product that’s certified by a reputable third-party, explains Andrew, can increase your confidence that the filter actually does what it says. 

What is water filter certification? 

Rather than addressing specific contaminants, water filter certification represents independent verification that a product meets established standards for safety, performance, and quality.
“Water filter certifications are highly respected in the industry and with consumers to ensure the products they’re certifying can be trusted and are known to be very safe and effective,” says Andrew.

Think of certification as a measure of confidence rather than a universal stamp of approval: It tells you a specific filter has met certain independently verified standards, but you still need to check which specific contaminants it’s been certified to reduce. This is easy to do online: “Each certifying body has a website on which they have their own up-to-date certification listings,” says Andrew. “Each one will mention specific contaminants that are certified for a particular product.”

Water treatment products can be certified to standards developed through an American National Standards Institute (ANSI)-accredited process. The standards all have a designation of NSF/ANSI, followed by a specific number that corresponds to a standard. “Each standard is specific to the technology treating the water, and sometimes the contaminant reduction claims being made,” says Andrew.

For example, NSF/ANSI 42 covers filtration systems designed to reduce aesthetic impurities, such as chlorine taste and odor, while NSF/ANSI 53 addresses contaminants that may have health effects, such as lead and PFAS.

Below, learn more about the three most common water filter certifications you might see on products, and how to choose a water filter that supports safer water in your home.

What does NSF certification mean? 

NSF, formerly known as the National Sanitation Foundation, is an organization that tests and certifies water filters according to American National Standards. “These standards cover the safety of materials in contact with drinking water, structural integrity if it’s connected to plumbing, and contaminant reduction claims made by the manufacturer,” says Andrew.

You’ll know a product is NSF-certified if you see a blue circle with the letters “NSF” inside of it. NSF is one of several accredited third-party organizations that can certify water treatment products. So while you may commonly see the NSF mark on filters, it’s not the only legitimate or respected certification out there.

What does IAPMO certification mean? 

IAPMO, or the International Association of Plumbing and Mechanical Officials, is another trade association that consists of plumbing experts and plumbing inspectors. IAPMO also operates an accredited, independent testing and certification body that operates similarly to NSF and WQA. 

Through its water systems certification program, IAPMO tests and certifies water treatment products to applicable industry standards, including NSF/ANSI standards. Products that meet its requirements may carry an IAPMO certification mark, which you can look for on the product or packaging.

What does WQA certification mean? 

WQA, or the Water Quality Association, is a trade association of filter manufacturers and water treatment experts. This organization also conducts independent testing and certification of water treatment products. Importantly, and like NSF and IAPMOO, WQA is accredited to ensure consistency and quality in its certification process. 

Products that meet WQA’s requirements typically carry the WQA Gold Seal, indicating they’ve been independently tested and certified to applicable industry standards. The Gold Seal program covers a range of drinking water treatment products, including filters, reverse osmosis systems, and water softeners. As with other certifications, check the product listing to see exactly which standards and contaminant-reduction claims have been verified.

What filter targets PFAS?

Two different filtration technologies have been tested to reduce PFAS in water. “The NSF/ANSI 53 certification addresses compounds in tap water that have been shown to affect health, which includes PFAS,” says Andrew. This particular certification covers typical water filters that use activated carbon.

A second option relies on a different mechanism entirely. “Reverse osmosis systems use different technology, which works by forcing water through a semipermeable membrane that allows water molecules to pass through while blocking PFAS and other contaminants.” These systems would be labeled with a NSF/ANSI 58 certification and a PFAS reduction claim. 

No matter which type of filtration system you choose, always check the product label and certification body’s directory to verify the PFAS reduction claim.

How to choose a water filter

The first step to finding the best water filter for you is finding out what’s in your water. When you understand which contaminants are present in your tap water, you can make an informed decision to buy one that actually reduces those specific compounds. If you’re on a public water supply, you can review your Consumer Confidence Report to learn more about where your drinking water comes from, how it’s treated, and potential contaminants. 

A lot can change between your water supply and your tap, so consider this information a starting place. Since municipal water reports only reflect what leaves the treatment plant and not what travels through aging mains and home plumbing to reach a tap, at-home options like ROSE's water test are built to catch what accumulates along the way.

Andrew recommends a laboratory test kit, like the ROSE water test, that involves sending water samples to a lab that analyzes them using evidence-based tools. Then, pick a filter that’s certified to address those specific chemicals. 

It’s also important to choose a filter that fits your lifestyle and needs. For example, countertop filters that connect directly to your faucet require no installation, and they’re often affordable options. The trade-off is they occupy counter real estate. Under-sink filters are hidden beneath your tap, but you may need to install an auxiliary faucet to make it work. Reverse osmosis filters are often more comprehensive in reducing contaminants, but they’re more costly and can require professional installation. 

While it can feel overwhelming to consider the potential health effects of your water, you’re not helpless to take action toward protecting you and your family’s health. “We can take control of our drinking water and our overall health,” says Andrew. “The way we do this is having our drinking water tested and choosing a filtration system that’s independently certified to treat those contaminants.” 

FAQs

What water filter certifications should I look for to reduce harmful chemicals in drinking water?

Look for a filter that’s certified to reduce the specific contaminants you’re concerned about, not simply one labeled “certified.” For example: the certification NSF/ANSI 53 covers health-related contaminant reduction claims, while NSF/ANSI 401 addresses certain emerging contaminants, such as some pesticides, Bisphenol A (BPA), and medication residue that may be present in water. Always check the product’s specific contaminant-reduction claims.

Are NSF-certified water filters better than uncertified filters?

Not necessarily. NSF certification doesn’t guarantee a water filter is better than every uncertified option. It does, however, provide independent verification that the filter meets specific standards for safety and performance. Certification can give you more confidence that a filter has been tested to reduce the contaminants it claims to target. 

Does a certified water filter remove all contaminants from drinking water?

No. A water filter’s certification only verifies the standards and specific contaminant-reduction claims for which it was tested. A filter certified to reduce chlorine, for example, isn’t necessarily certified to reduce lead or PFAS. Check both the certification standard and the individual contaminants listed on the product.