Uncertified water filters of Amazon

Home water filter with clear water on windowsill

Not surprisingly, we spend a lot of our time reviewing water filters. So when it comes to making sure products are able to remove unwanted contaminants from your tap supply, we know what to look for.

With Amazon often finding itself in the spotlight for selling subpar or counterfeit goods on its marketplace, we decided to find out exactly how many of the water filtration products listed by the retail giant can back up their claims with genuine filtering certifications.

We looked into over 550 of Amazon’s top water filter products, cross-referencing them with NSF water filter certifications. The results? Well, let’s just say that we’re going to be reading Amazon product descriptions pretty closely from now on.

Here are the findings from our research, plus some key pieces of information on water filter certifications, and how to source legit filtration products.

What did we find when we reviewed Amazon’s water filters?

Key findings

Of the top 590 filter products listed on the Amazon.com marketplace in October 2020, only 102 cited a relevant NSF/ANSI standard that matched their filtering claims.
An additional 66 filters did possess NSF/ANSI certification in some form. However, a general certification doesn’t guarantee that a filter has been tested and approved for its intended purpose.
71.5 percent of Amazon’s top listed filters have no NSF/ANSI certification whatsoever. While it’s important to say that some brands are selective about which products they submit for NSF testing (Brita being the most famous example), this leaves consumers without a way to independently verify the credentials of many top-selling filtration products

Full results

Here are the full results of our survey, split into the major filter types—pitcher and countertop filters, reverse osmosis filters, refrigerator, and MWF filters, under-sink filters, portable filters, well water filtrations systems, and water softeners.

Wellwater filtration systems

48 filter products were checked.
10 were NSF/ANSI certified to an appropriate standard.*
5 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standard 58 was the most common.
The remaining were not certified nor claimed to be certified

* While these filters are certified with a relevant NSF/ANSI code, they may not be sufficient to properly filter well water alone. The best well water filtration systems combine several filtration elements, alongside a pre-screening filter to remove sediment.

What might no certification mean for a well water filter? Based on the 2017 US Census American Housing Survey, it’s estimated that over 13 million households rely on private wells for drinking water across the country. Groundwater that doesn’t pass through public treatment works is at greater risk of contamination from a variety of sources, including agricultural runoff, waterborne bacteria, and wash from heavy rain. For well users, a good filtration system is often the only line of defense against these possible contaminants.

Water softeners

41 products were checked.
4 were NSF/ANSI certified to an appropriate standard.
6 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standards 58 and 42 were the most common.
Weirdly, none of the Amazon water softeners we looked at were rated for NSF/ANSI standard 44. This is the code for water softeners using a cation exchange system—one of the most common softening methods.

What might no certification mean for a water softener? The lack of water softener-specific codes for Amazon’s top softener products is disconcerting, but it also reflects the fact that many of the products we checked are actually water filters that offer softening as an additional element. Nevertheless, each claim made by a filtration product should be accompanied by an appropriate NSF/ANSI code to give consumers full confidence. Well water softeners, for example, often claim to filter other contaminants too.

Reverse osmosis filters

88 reverse osmosis (RO) filter products were checked
16 were NSF/ANSI certified to an appropriate standard.
15 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standard 58 was the most common.

What might no certification mean for an RO filter? Many people use reverse osmosis filters, which pass water through micro-membranes, to protect themselves from possibly harmful contaminants. Homeowners who source their water from a private well may rely on systems including an RO element to protect themselves and their families from microorganisms, heavy metals, and unwanted chemicals, so a lack of genuine certification should send alarm bells ringing.

Undersink filters

89 under-sink filter products were checked.
8 were NSF/ANSI certified to an appropriate standard.
18 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standard 58 was the most common.

What might no certification mean for an under-sink filter? Under-sink filters are another type of filter design intended to be out-of-sight, out-of-mind. This is a great feature, as long as you don’t need to worry about whether they’re actually working. Under-sink models offer different degrees of filtration depending on their filter element (e.g. carbon, reverse osmosis, etc), and are rarely relied upon in serious contamination cases. Again, however, a lack of testing leaves consumers in the dark about the contaminants they’re actually consuming.

Refrigerator filters

74 generic and MWF refrigerator filter products were checked.
7 were NSF/ANSI certified to an appropriate standard.
2 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standard 372 was the most common.

What might no certification mean for a refrigerator filter? The convenience of refrigerator filters means they often fly under the radar when it’s time for replacement cartridges or cleaning. This makes them one of the most bacteria-prone appliances in our homes. Add to that the chance that your filter contains no reliable purifying element, and you have an appliance that’s adding no value to your water.

Complicating this category is the fact that some refrigerator manufacturers source filter components from third party suppliers, while others don’t submit their filters for NSF testing (e.g. Bosch). In addition, some refrigerator filters are only compatible with certain filter cartridges. GE fridge filters, for example, are only intended to work with genuine GE MWF filter cartridges. This doesn’t stop Amazon from selling, and many people from using, off-brand alternatives.

Pitchers and countertop filters

161 pitcher and countertop filter products were checked.
38 were NSF/ANSI certified to an appropriate standard.
19 were listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standards 42, 53, and 58 were the most common.
This category included several Brita products that aren’t submitted for NSF testing.

What might no certification mean for a pitcher or countertop filter? Pitcher filters are the classic hand-held design pioneered by Brita, while countertop models sit on the counter and may or may not attach directly to the faucet. It’s unlikely that consumers will use these filters to protect themselves from serious health hazards, but people still expect these products to purify water of common pollutants, as well as nasty flavors. Using an uncertified pitcher filter on a regular basis can leave people with a false sense of security and exposure to volatile organic compounds (VOCs) that may be potentially harmful when consumed over a long term.

Portable filters

89 under-sink filter products were checked.
19 were NSF/ANSI certified to an appropriate standard.
1 was listed as certified but didn’t cite an NSF/ANSI standard.
Of those certified, NSF/ANSI standard 372 was the most common.

What might no certification mean for a portable filter? This is another important category, as we rely on portable filters when we can’t trust the quality of water outside our homes. An unsuitable portable filter could mean consumers are filling up from sources they really shouldn’t be. This category also contained Brita products, who don’t always work with the NSF.

Understanding the results

Who is the NSF?

NSF International is a major globally recognized independent organization that sets standards for safe and effective consumer goods, especially those involving food and water processing. They also test and certify products according to their own standards.

NSF develops their standards in collaboration with national arbitrators such as the Environmental Protection Agency (EPA) and are accepted by the American National Standards Institute (ANSI).

When it comes to home and commercial water filters, NSF has led the development of the American National Standards (ANS) since the 1970s. While manufacturers aren’t legally required to submit their products for NSF evaluation, those that do are subjected to rigorous testing in their Michigan-based labs.

Aside from the NSF, there are other reputable water testing boards, including The International Organization for Standardization based in Switzerland. All major testing or certification bodies, including the ANSI, WQA, and the CAN in Canada, certify products against NSF codes.

NSF/ANSI standards

Here’s a quick reference table on what the NSF/ANSI standards mean:

NSF/ANSI certification	Frequently tested devices	What do these filters remove?
42, 53	Pitcher, faucet, refrigerator, and other activated carbon filters	Organic contaminants Chlorination byproducts Cleaning solvents, pesticides Cryptosporidium Lead
58	Reverse osmosis (RO) filters	Most bacteria and viruses Nitrates Sodium Dissolved inorganics organic compounds Pesticides and petrochemicals
55, 244	Ultraviolet (UV) filters	Bacteria Viruses

NSF/ANSI 42.

This covers aesthetic claims, meaning that a filter can remove non-health-related contaminants and improve the flavor or appearance of water. It also ensures the safety of filter materials and product integrity.

NSF/ANSI 53.

This means that a filter is capable of reducing lead, volatile organic chemicals (VOCs), or health-related bacterial contaminants such as Cryptosporidium and Giardia.

NSF/ANSI 58.

This is the reverse osmosis filter standard. When an RO filter meets this certification, it can reduce the presence of cysts, bacteria, and nitrates.

NSF/ANSI 244.

This means that a filter can reduce microorganisms, bacteria, viruses, and cysts to create microbiologically safe drinking water.

NSF/ANSI 55.

This is the standard for UV water treatment. Certified filters can disinfect microorganisms including bacteria and viruses through UV radiation.

NSF/ANSI 44:

This is the standard for water softeners using cation exchange.

NSF/ANSI 372:

This sets acceptable lead content and leaching within products themselves.

NSF/ANSI 401:

This is a newer standard that addresses up to fifteen individual contaminants, which have been identified in published studies as regularly present in drinking water. These include medications, herbicides, DEET insect repellent, and BPA plastics.

biological test of the water. Soft-focused, focal point is on the hands

How to spot an uncertified water filter

Here are our top five tips to ensure you’re purchasing a water filter that will genuinely improve the taste of your tap supply and protect from possible pollutants:

1. Look for brands being tricky with their product descriptions

There are many ways to present the benefits and pros of a particular product, but only one way of saying that a filter product is certified and listed by the NSF. Unless they explicitly recuse themselves from NSF testing for their own reasons, all legit filter products should use clear, unambiguous language such as:

Tested by the NSF
Certified by the NSF
Listed by the NSF
Certified by the NSF to standard X

If a brand is using language that suggests its products comply with NSF standards, but not that products are tested or certified by the NSF, you may want to consider other options.

2. Know your certifications (and what’s not covered)

Because NSF standards often cover more than one contaminant, it’s important that you check for specific claims alongside the correct certification. For example, if you’re looking for a countertop filter that effectively reduces lead, make sure the product description lists lead as one of the contaminants that will be reduced and that it’s tested to NSF/ANSI 58.

A minority of brands will attempt to be outright deceptive, by earning certification for one NSF standard and then using it to claim other, untested benefits. For example, A filter might be genuinely certified to remove unpleasant odors from water (NSF/ANSI 42) but then mislead consumers by using that certification to advertise it’s lead-reducing credentials.

3. Ask for performance data

To accurately fact check product claims, look for performance data sheets that show the exact filtering credentials of a product for all possible contaminants. If performance data isn’t easily accessible, then you can always contact the manufacturer and ask. Brands with your interests at heart will be more than happy to provide you with the right information, while those that put profits before product quality may be unwilling to respond.

4. Use the publicly available WQA and NSF databases

Just like the NSF international’s Certified Product and Service Listings we used to check up on Amazon’s top filter products, most product testing boards make their directories publicly available online. This means it’s super easy to check whether the products you’re interested in are actually listed.

5. Find a trustworthy review site

Just because a website recommends a particular filter, it doesn’t mean you should automatically assume it’s the best option for you. When as many as 61 percent of the product reviews in certain Amazon categories may be considered fake (according to a 2018 study), it pays to make some critical judgments about the sources of your information.

For example, are your recommenders water filter experts, or do they review all types of products? Does a site provide unbiased opinions on the best filters for a specific need, or do they obviously favor a particular brand? And do they seem genuinely passionate about the health and environmental benefits of water filters, or are they more interested in sales?

The takeaway?

Until Amazon is held more accountable for the quality of the products on their marketplace, there will always be an added risk factor when shopping on their site. If that means receiving the wrong type of shampoo or a counterfeit t-shirt, you might feel pretty annoyed. But the consequences of misleading filtration products, which can mean the difference between drinking safe and potentially hazardous water, are much more serious.

As is the case with many elements of our national infrastructure, there’s growing skepticism over the quality of water produced by public treatment works. Thanks to increasing demand, spending cuts, and the effects of climate change, water sources are quickly degrading in some states. Meanwhile, advocacy groups and charities are claiming that EPA limits on acceptable contaminants are nowhere near stringent enough to produce a healthy drinking supply—all of which adds to the idea that filtering tap water may soon be seen as a necessity instead of a luxury.