Rating the Best Water Filters (and why you should have one)

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Written by Leigh Matthews

Last updated on February 1, 2019

Whether you’re interested in water filters or purification for aesthetic or health reasons, the right kind of system can make a real difference to the quality of the water in your home. Given that the human body comprises about 55-65% water, wouldn’t you want to make sure that water is safe?

The United States Environmental Protection Agency (EPA) estimates that 1 in 12 Americans is exposed to potentially harmful microbes, pesticides, lead, or radioactive radon with every drink of tap water and every time they take a shower (R). For Native Americans living on tribal land, this figure rises to a staggering 1 in 4 without access to safe water in their homes. In Canada, some communities have been without safe drinking water for decades, and while many of us in big cities are quite nonchalant about our water, in some ways our tap water has never been more vulnerable to safety issues.

The chemicals and organisms contaminating drinking water can cause infection, poisoning, endocrine (hormone) disruption, and a host of health conditions. Poor water safety can cause serious disease outbreaks, shorten lifespan, reduce quality of life, and affect childhood growth and development. The main reasons for water contamination include:

  • Crumbling water treatment infrastructure
  • Hazardous agricultural practices (largely animal agriculture and feed lots)
  • Fracking, oil and gas pipelines, and other industrial activities
  • Failing environmental protections and oversight.

As a result of these factors, even in economically developed countries millions of people are living without safe, potable water in their homes.

Fortunately, innovative new technologies mean that, while governments play catch up, we can quickly and easily use water filtration systems at home to dramatically improve the potability and safety of what comes out of our faucets. And, home filtration systems are nothing new. Humans have been filtering water at home since 4,000 B.C. or so, with charcoal, sunlight, boiling, and mechanical filtering all popular methods in Ancient Greek and Roman times.

Of course, our ancestors didn’t have the benefit of being able to test drinking water for safety like we do. And, thanks to new technology, home water filtration is now simple and easy to install and use every day.

Looking for a water filter for your shower? We’ve written on those too, check them out over here.

Our top picks for eco-friendly Water Filters

ProductHighlightsLeaf Score Product Link

Watts Premier RO-Pure Plus 531417

Read the Review
  • Ideal for daily use and maintenance is incredibly convenient
  • Unit filters out sediment, particulate, chlorine, taste and odor, sodium, chromium, arsenic, copper, lead, cysts, giardia, VOCs, and many other contaminants
  • Certified by WQA to NSF/ANSI Standard 58 and Standard 372 (lead-free)
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iSpring RCC7 75 GPD

Read the Review
  • Can produce 75 gallons of water per day; more than double most other systems
  • Capable of removing 97.2% of Total Dissolved Solids, including chlorine, taste, odor, fluoride, arsenic, lead, chromium and radon
  • Filters can be a bit fiddly to change
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Aquasana OptimH2O Reverse Osmosis Water Filter with Remineralizer and Brushed Nickel Faucet

Read the Review
  • It is not only certified to NSF 53, it is also tested and certified to meet standards 42, 58, and 401 (the Emerging Compounds standard) as well as P473
  • The unit offers instant access to healthy water by providing 0.5 gallons per minute
  • This RO system also improves water pH balance for optimally alkaline drinking water
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Pelican Water PUV-8 and PUV-16 Premium UV Water Treatment and Disinfection Systems

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  • Provides natural and safe disinfection without the use of harmful chemicals
  • These systems are effective against a broader range of organisms than chlorine, and are capable of destroying E. coli, Cryptosporidium and Giardia
  • made with a stainless steel exterior that resists rust and corrosion
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Viqua SV8Q-PA NSF Class B UV Water Purification System

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  • This whole-house system is easy to maintain and provides a flow rate up to 7 GPM, slightly exceeding the average household rate of 6 GPM
  • One of few UV systems certified to NSF Standard 55 Class B
  • Not suitable for untreated well water or areas where water isn't already deemed potable and safe
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Viqua E4-V UV Class B Disinfection System

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  • The VIQUA E4-V disinfection system is durable and will disinfect virtually all bacteria, viruses and pathogens
  • The Viqua E4-V takes just 1 or 2 seconds to destroy harmful bacteria, without the use of chlorine or other chemicals
  • Class B devices are intended for use with water that is already deemed potable and safe
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Viqua Pro10 UltraViolet (UV) Disinfection System

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  • One of the few fully NSF certified to NSF/ANSI Standard 55 Class A
  • UV intensity monitor with diagnostics makes it easy to monitor performance
  • The UV lamp has twice the output of current high-output lamps but the CoolTouch fan significantly reduces water temperature
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Big Berkey BK4X2 Countertop Water Filter System with 2 Black Berkey Elements and 2 Fluoride Filters

Read the Review
  • Because Berkey refuse to get their products certified to NSF standards, it is difficult if not impossible to compare the Berkey to other water filters
  • The design of the Berkey means that water does not fully drain from the top, with around an inch of water sitting around the plugs at any given time
  • Many customers have complained about poor response times and refusals to replace or refund malfunctioning products
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Aquasana AQ-4000

Read the Review
  • The Aquasana AQ-4000 is certified to meet NSF standards 401, 42, and 53, as well as P473
  • One Aquasana Claryum filter has 11 times the capacity of the leading gravity-based pitcher, making this a very cost-effective option
  • This system reduces or removes at least 77 listed contaminants, including herbicides, pesticides and VOCs, atrazine, and PFOA & PFOS
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ZeroWater 40 Cup Ready-Pour Glass Dispenser

Read the Review
  • Certified to NSF Standard 53, demonstrating that it can reduce both lead and chromium, as well as a range of other chemicals
  • ZeroWater use both activated carbon and ion exchange to reduce contaminants, including removing dust, rust, and other suspended solids
  • this pitcher removes 99.6% of total dissolved solids (TDS), which includes removing essential minerals such as calcium, magnesium, and potassium
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iSpring WGB32B 3-Stage Whole House Water Filtration System

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  • It has a 100,000-gallon capacity activated carbon filter that should cover a household of four for a year
  • The iSpring is certified by the NSF to remove any particles larger than 5 microns and is effective at removing chlorine, sediment, herbicides, pesticides, rust, and up to 95% of the contaminants in your water
  • This system is equipped with three stage filtration but, unlike an RO system, it does not reduce Total Dissolved Solids (TDS), meaning that it retains the healthy minerals in your water
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Aquasana 10-Year, 1,000,000 Gallon Whole House Water Filter with Salt-Free Softener, UV Filtration, and Professional Installation Kit

Read the Review
  • This Aquasana system has a 5-stage filtration process that removes or reduces at least 75 contaminants including lead, mercury, and pesticides
  • Thanks to UV Sterilight Filtration, this system also addresses microbial contamination, removing 99.99% of viruses and bacteria like e-coli and chlorine resistant cysts like giardia and cryptosporidium
  • The dual tank Simply Soft salt-free descaler is included to offer scale prevention for the entire house without the use of chemicals or salt
View on Amazon

Things to consider in Water Filters

Types of Water Filtration System

Water filtration systems fall into two main categories:

  1. Point-of-use (POU) systems, which treat the water just before you use it, such as in a shower head, faucet, or water pitcher.
  2. Whole-house/point-of-entry (POE) systems, which treat the water as it enters your home (or business), after which the water continues on to all points of use.

Whole-home systems are usually installed near to a water meter if you live within a city’s water supply, or close to a pressurized storage tank if you are on a well water system.

Whole home water filtration systems

Whole home water filter systems are increasingly popular as, once you’ve got one installed, they’re effective, produce clean and clear water, and are fairly easy to maintain. Home water filtration systems can also be better for the environment than some other filter systems as they don’t require significant energy to function and usually run effectively for many years without needing replacement parts.

Filtered water pitchers

If your budget doesn’t quite stretch to a Berkey or a complete home filtration system, a simple water pitcher with a filter can still help clean up your tap water. There is a lot of variation in these pitchers, with some providing robust filtration for a variety of potential contaminants while others do very little.

To make sure you get an effective water filter pitcher, opt for a product with NSF certification. Then, grab a reusable bottle and fill it up from your Berkey or with filtered tap water, so you can feel good about what you’re drinking every day and keep your use of plastic water bottles to a minimum.

Why should you use a home water filtration system?

An effective water filtration system is a good idea for every home, given the potential for contamination and the low standards set by many governmental bodies. Regulators are mostly concerned with basic water safety (is it riddled with bacteria and lead) rather than testing water to see if it is optimal for consumption in the home. And, when it comes to water contamination, what doesn’t kill you (in the short term) certainly isn’t likely to make you any stronger going forward.

Water filtration is particularly important for individuals who are more sensitive to contaminants or more at risk to infections than the general population. This includes young children, older adults, and people with impaired immune, liver, or kidney function. Depending on where you live, your health, medications, metabolism, diet, and genetics, the water you drink every day could prove problematic if unfiltered. Some regions have a high copper content, for example, which may leave your body low in zinc. Other areas have water high in iron, added fluoride and chloride, and other elements that may interact with your medications and basic physiological processes. And, of course, there’s always the risk of microbes, benzene, radionucleides, arsenic, and nitrates that can have adverse health effects.

Water contaminants

Some of the contaminants that can be found in tap water, well water, and other water sources people drink every day worldwide include:

  • Viruses and bacteria – including coliphage, Escherichia coli, Salmonella enterica, Giardia, Cryptosporidium
  • Trihalomethanes – including bromodichloromethane, bromoform, chloroform, and dibromochloromethane
  • Inorganic minerals – including chloramine, chloride, free and total chlorine
  • Heavy metals – including aluminum, antimony, arsenic, barium, beryllium, bismuth, cadmium, cobalt, chromium, copper, iron, lead, manganese, mercury, molybdenum, nickel, vanadium, and zinc
  • Pharmaceuticals – including, acetaminophen, caffeine, carbamazepine, ciprofloxacin, erythromycin, sulfamethoxazole, trimethoprim, bisphenol A, diclofenac, progesterone, ibuprofen, naproxen, and triclosan.

Other contaminants can include crude oil, kerosene, mineral spirits, diesel, selenium, thallium, rust, silt, sediment, foul tastes and odors, and polychlorinated biphenyls (PCBs).

Arsenic contamination of drinking water is a serious health risk for hundreds of millions of people worldwide. In the U.S., 43 million people use private wells for water, and an estimated 3 million people drink well water that contains arsenic levels above the World Health Organization (WHO) standard and the EPA maximum contaminant level (MCL) of 10 μg/L (R). The responsibility for testing well water rests with the individual homeowner, who will then need to take steps to reduce arsenic content if it is high. Methods for arsenic removal include anion exchange, adsorptive media and reverse osmosis.

Lead is often a problem in old houses where plumbing had not been updated. This heavy metal is very harmful to health, so if you aren’t sure if your home has lead pipes, contact your water utility or your health department and ask if there are lead pipes and/or if they can test your water supply for lead. Replacing lead pipes is the best option but, in the meantime, it is a good idea to use filter technology to remove lead from your water.

Depending on where you live, you may be able to access a recent water quality report which will tell you what contaminants are typically found in the ‘raw’ water supply as well as the water that ultimately reaches your taps. The report may also offer information on the methods used by your local water utility to treat or eliminate any contaminants. If you are in the US (or in some places in Canada), you can ask for a water quality report (called a CCR or consumer confidence report) from your local water utility/authority. If your household water comes from a well system, you might consider having the water independently tested.

Once you have seen a recent CCR or results of independent testing you will be much better positioned to decide on the right kind of water filtration system or systems for your home and family.

Why filter your shower and laundry water?

The first thing to understand about the water you shower and bathe in is that it is normally pre-treated with chemicals such as chlorine to kill potential pathogens. These chemicals do not magically disappear after use and, as such, the water that enters your home can contain residues of chlorine and other disinfection by-products (DBPs).

See what we have to say about shower filters over here.

Water filtration and purification technologies

Although the words filtration and purification are often used interchangeably, the two terms are not synonymous. Water filtration is simply that: filtering water to remove larger contaminants. Purification removes almost all contaminants, no matter how small. As such, filtration systems should only be used on water that has already been treated for contamination, while purification systems can be used on highly contaminated or untreated water.

To be certified as a water purification system, a unit needs to be able to remove at least 95% of contaminants. Most reverse osmosis systems will remove up to 99% of contaminants. In contrast, filtration systems can help make water clearer and odor free, but the water may still be harmful to health if not treated for contamination in some other way.

Let’s take a look at two purification systems first and then options for water filtration at home, with recommendations for some of the best water filtration and purification systems on the market currently.


Distillation is an effective water treatment technology for use in the home and in a commercial capacity. This process purifies water by boiling it in a container, collecting the steam in a series of cooling tubes, and then condensing the steam in a second container to give distilled water. Almost all of the original water’s impurities remain in the first container, and the process is effective for removing:

  • Nitrates
  • Bacteria
  • Sodium
  • Hardness (calcium salts, for instance)
  • Dissolved solids
  • Most organic compounds
  • Lead.

Distillation does not always remove contaminants that can be turned into gases, however, including gasoline components and radon. Some distillation systems do contain filters that remove these contaminants, or a separate filter can be used after distillation (R).

It’s also important to note that distilled water lacks any salts, including sodium and calcium salts that the human body needs as electrolytes. Drinking a lot of distilled water exclusively could make you feel thirsty as your body can have problems holding onto water without the right electrolyte balance. Water filtration systems that work by distillation have been shown to remove fluoride at a high rate (R).

Reverse osmosis

Reverse osmosis (RO) is a popular water purification technique that removes numerous contaminants and produces clear, odor free water. It was originally developed to process saltwater into freshwater and uses a semi-permeable membrane to filter out contaminants as water is forced through the membrane at high pressure. RO systems have also been shown to remove fluoride at a high rate (R), and RO systems also remove other elements, resulting in an acidic hypotonic water. For this reason, some people choose to add minerals back into water that has been purified using reverse osmosis.

High quality RO systems do a first pass to filter out larger particles, and then send pressurized water through the membrane to filter out impurities as small as 0.001 microns, resulting in safe, clean, drinking water. Two of the best RO systems are the Watts Premier RO-Pure Plus 5314117 and the iSpring 75GPD 5-Stage Water Filter.

A quality whole-home reverse osmosis system removes 98-99% of most contaminants including Total Dissolved Solids (TDS), sodium, chloride, sulfate, nitrate, arsenic and numerous other chemical and organic contaminants. What these systems don’t remove, however, are any iron, sulfur, manganese, tannin and other problematic elements present in well water. In fact, these need to be removed before reverse osmosis can occur.

As such, a whole-home RO system might well include:

  • Pre-treatment filtration system
  • RO system
  • Atmospheric storage tank
  • Re-pressurization pump
  • Ultraviolet light or Quantum Disinfection system
  • Calcite filter (to raise water pH or add back useful TDS).

Hard water (above 7 parts per million) that is intended for an RO system first needs to be softened or de-scaled, so as to prevent the membranes from becoming coated with limescale.

If the water entering your house comes from a well, consider a 4-stage filtration system that includes pre-filtration prior to RO. For near-surface well water you may need a 7-stage filtration system. If your house is hooked up to your city’s water supply, though, you could save money by opting for a 3-stage system as water will have already undergone some degree of filtration and be ready for RO.

As a final step, be sure to check on the gallons per day rating of your equipment, which is often notated with the abbreviation “GPD”. A system rating of 300 indicates that a maximum of 300 gallons of drinking water can be produced. Most systems can produce between 50-75% of this rating on a daily basis, assuming that local water pressures are between 40-60 PSI.

UV filters

Ultraviolet (UV) filtration systems are a relatively environmentally friendly water purification option and one of the newest water treatment technologies. These systems use UV light to destroy bacteria and don’t involve the use of chemicals or heat, making them relatively inexpensive to run once set-up. That said, they can be fiddly to set up, particularly if you’re installing a complete home filtration system to purify all the water that enters the house. And, once set up, yearly maintenance is required, and some parts may need replacing every so often.

The capacity for these systems ranges from 1 gallon-per-minute up to 40 gallons-per-minute. A UV water purification system effectively destroys 99.9% of waterborne microorganisms including chlorine-resistant microorganisms such as Giardia and Cryptosporidium. Two of the best options for UV purification are the HQUA Ultraviolet Water Purifier and the VIQUA, which are listed in the ecoHome directory.

UV systems do have several disadvantages, however. This technology does not remove any other contaminants from water, meaning that separate filtration systems need to be used to remove heavy metals, salts, chlorine, gasoline products, pharmaceuticals, and so forth. In addition, the UV filter only works for ‘clear’ water, so a first-pass filtration will need to be done if water is cloudy or full of sediment. UV systems also require electricity, so are not suitable for rural or emergency needs.

If the water in your home is already relatively clear and you’re looking for a way to ensure it is free from microbial contaminants, a UV system might be right for you.

Activated carbon filtration

Activated carbon filters are typically effective at removing some but not all impurities from water, with a few exceptions, such as the Berkey system which goes above and beyond. When bike touring in remote areas with no potable water sources, I have made use of travel-size bottles that incorporate this filtration technology to quickly filter water from rivers. These filters are good for removing sediment and silt from water as they attract and absorb these particles, and they are also fairly effective at removing chlorine and other larger contaminants.

Most activated charcoal filters do not remove smaller microorganisms, so it is generally a good idea to use these in combination with other types of filtration technology or water purification, such as RO, distillation, and iodine treatment. There are some exceptions, with some systems able to remove some organisms and toxins produced by these organisms, such as cyanotoxins produced by blue green algae (R). As such, it is best to go for a system that has been independently certified for its capacity to purify rather than simply filter water.

Faucet filters incorporating activated carbon technology offer an inexpensive way to quickly filter tap water at home. These may be a good option if your water is treated for microbial contamination but is often hard, cloudy, fluoridated or chlorinated to excess. Some systems are certified to reduce sediment, bacteria, microorganisms, cysts, chlorine, and other contaminants from water, including the relatively inexpensive DuPont WFFM100XCH Premier Faucet Mount Drinking Water Filter. This system can filter 100 gallons of water, meaning that it’s best to change the filters at least every two months.

The best activated carbon filtration and purification system available, however, is hands-down the Berkey. This power gravity filtration and purification system uses self-sterilizing and cleanable elements with micro-pores small enough to stop pathogenic bacteria from passing through. The Black Berkey filters have consistently performed at a high level in independent third-party testing, helping to remove 99.999999% of contaminants. The ceramic filters contain granular activated carbon and are just as effective but are slightly more durable for traveling.

Gravity filtration is a popular option for relief organizations such as UNICEF, the Peace Corps, and the Red Cross. This is because systems like the Berkey are portable, require no plumbing knowledge or household modifications to set up, and don’t require electricity. They can easily purify tap water, but really shine when used to purify untreated water from lakes and streams. The Berkey not only looks great in the kitchen, then, it is also the perfect camping companion. And, the Berkey is invaluable in the event of an earthquake, blackout, hurricane, flood, or other local or national emergency when treated tap water may not be available.

The Berkey filters out cysts and parasites and unhealthy chemical contaminants and impurities, but retains essential minerals, making the resulting water arguably healthier than water produced by distillation or RO. The durable filters can process up to 3,000 gallons of water, meaning that at a rate of ten gallons a week, the filters can last up to eleven and a half years. Specialized Berkey filters can also remove fluoride and arsenic.

In order to be classified as a water purifier, a water treatment device must remove at least 99.9999% of pathogenic bacteria and reduce viruses by 99.99%. The Black Berkey Purification Elements remove 99.9999999% of pathogenic bacteria and 99.999% of viruses, greatly exceeding the standards required for purification status and earning them the seal of approval by State and EPA accredited laboratories testing for NSF/ANSI Standard 53.

The best option for home water filtration is an active carbon filtration system that is refined enough to not only eliminate heavy metals, sediment, pesticides, and VOCs, but also microbes and other nasties.

Top Tip – Alkaline and water ionizer systems are not filtration or purification systems. These systems simply pass water over electrically charged plates to separate alkaline and acidic water. The resulting alkaline water is softer and negatively charged. This is the same for infrared filters which use heat and light to negatively charge water. These two types of system can be useful if you live in an area with hard water but should be combined with actual filtration or purification technology.

What about bottled water?

If there are benefits to filtering and/or purifying tap water, doesn’t it just make the most sense to switch to bottled water and let someone else do all the hard work for you? In short, no. Bottled water is supposed to be tested for some contaminants, but not every bottle will have gone through the same quality control, and the levels set by the US Food and Drug Administration for contaminants aren’t always all that robust. Bottled water may also contain chlorine as some companies use this to disinfect the water, and, some bottled water contains fluoride either because it was present in the natural water source or has been added.

To find out what is in a bottle of water, the onus is on the consumer to call the bottling company and find out. NSF International is also a great resource for information as this non-profit organization provides resources on bottled water contaminants and safety and independently certifies filtration systems within the United States.

There’s also another problem with bottled water: the environmental impact. According to Penn State University, an estimated 42.6 billion plastic water bottles are purchased each year in the U.S., at a total cost of around $11.8 million for consumers. As a rough estimate, using a $20 reusable water bottle, filled using tap water filtered through a $300 home system, could save an individual as much as $5800 over five years. And, if you look after your reusable bottle and properly maintain the filtration system, the savings will continue to rack up over subsequent years.

Switching to a reusable bottle could save around 217 plastic water bottles from going into landfill every year (R). And, good quality reusable bottles are also free from lead and BPA and reduce exposure to soft plastics that can leach harmful chemicals into the water, particularly if a plastic bottle is left in the sunshine or a hot place.

The takeaway

A whole home water filtration system is an ideal way to filter all of the water you use, be it for drinking, cooking, laundry, bathing or showering. It might sound like overkill to filter anything but your drinking water but filtering your shower water can have unexpected benefits. If you already have water purification and/or filtration systems set up for drinking water, check out the ecoHome directory to see the best standalone shower filter systems available. If you don’t, consider installing a whole home water filtration system right from the get-go.

Things to look for when buying a water filter

You’ll probably notice that some shower filters mention vitamin C, which might seem a little odd at first. There’s good reason for this, however. Vitamin C (as sodium ascorbate or ascorbic acid) rapidly neutralizes chlorine. As such, vitamin C has become quite popular with sanitation engineers who need to quickly and safely dechlorinate waste water before sending it back out into the natural environment.

Even a little bit of chlorine residue in treated waste water can have devastating effects on local wildlife. Happily, vitamin C is not toxic to wildlife and does not lower the dissolved oxygen in water as much as sulfur-based chemicals. Ascorbic acid is mildly acidic and reacts with chlorine to form hydrochloric acid. Don’t worry, though, this has a negligible effect on the pH of the water exiting your shower head. And, if a system uses sodium ascorbate, this is neutral and does not affect the water pH.

One other thing to watch out for with water filters, especially faucet and pitcher water filters, is the presence of antimicrobial substances and chemicals. For example, we would have included the DuPont WFFM100XCH Premier Faucet Mount Drinking Water Filter in our ecoHome directory if it wasn’t for the presence of Microban in the product. Microban is the trade name for triclosan, a chemical increasingly linked to the development of antibiotic resistance as well as detrimental effects on human health, soil health, aquatic plants, and the environment in general (R, R).

Water Filter Certifications

When looking for a water filter, check that it is certified by the National Sanitation Foundation (NSF). The NSF awards different levels of certification depending on which impurities a system filters out.

Different manufacturers focus on filtering out a range of different contaminants. NSF International verifies that a company’s filters do what they claim to do. Some products claim to filter for a specific contaminant, such as cadmium, but to be certain, check the packaging and product information for the applicable standard (such as NSF/ANSI 53 or NSF/ANSI 58).

NSF developed its first drinking water treatment standard in 1973. They now test against seven point-of-use/point-of-entry (POU/POE) drinking water treatment standards and are used to certify a wide range of water filtration systems. Some systems carry more than one certification because they use more than one treatment technology, such as a combination activated carbon and UV filter system, for example.

The seven NSF standards include three standards that cover filtration systems:

  1. NSF/ANSI 42
  2. NSF/ANSI 53
  3. NSF/ANSI 401.

NSF ANSI 42 – Drinking Water Treatment Units – Aesthetic Effects

This standard, which is typically associated with carbon filtration systems, certifies that a system meets the minimum requirements for reducing specific aesthetic or non-health-related impurities such as chlorine and taste or odor as well as particulates.

NSF/ANSI 42 covers material safety, structural integrity and aesthetic, non-health-related contaminant reduction performance claims.

NSF ANSI 53 – Drinking Water Treatment Units – Health Effects

NSF/ANSI 53 is awarded to filters shown to reduce at least one contaminant with a health effect. This standard, like NSF 42, typically applies to carbon filtration systems and covers material safety and structural integrity, but extends to cover health-related contaminant reduction performance claims.

These may include claims over reduction of CryptosporidiumGiardia, lead, volatile organic chemicals (VOCs) and MTBE (methyl tertiary-butyl ether) in drinking water.

NSF/ANSI 401 – Emerging Compounds/Incidental Contaminants

NSF/ANSI 401 extends coverage to certify a water treatment device’s capacity to remove up to 15 individual contaminants identified in published studies as occurring in drinking water at trace levels. These contaminants have not been deemed a public health issue but can affect perceptions of drinking water quality. This standard also applies to reverse osmosis (RO) water treatment systems.

The contaminants covered by NSF/ANSI 401 include:

Prescription Drugs

  • Meprobamate: a compound found in anti-anxiety drugs.
  • Phenytoin: an anti-epileptic drug.
  • Atenolol: a beta blocker drug.
  • Carbamazepine: an anti-convulsant and mood-stabilizing drug.
  • Trimethoprim: an antibiotic medication.
  • Estrone: a prescription birth control drug.

Over-the-Counter Medications

  • Ibuprofen: an over-the-counter pain reliever and anti-inflammatory medication.
  • Naproxen: an over-the-counter pain reliever and anti-inflammatory medication.

Herbicides and Pesticides

  • DEET (N,N-Diethyl-meta-toluamide): a pesticide and common active ingredient in insect repellents.
  • Metolachlor: an organic compound that is widely used as an herbicide.
  • Linuron: an herbicide often used in the control of grasses and weeds.

Chemical Compounds

  • TCEP (Tris(2-chloroethyl)phosphate): a chemical compound used as a flame retardant, plasticizer and viscosity regulator in various types of polymers including polyurethanes, polyester resins and polyacrylates.
  • TCPP (Tris(1-chloro-2-propyl) phosphate): a chemical compound used as a flame retardant.
  • BPA (Bisphenol A): a chemical compound used as a plasticizer.
  • Nonyl phenol: a collection of compounds often used as a precursor to commercial detergents.

In addition to the basic filtration standards above, NSF provides standards for specific types of water treatment or filtration systems.

These include

  • NSF/ANSI 44
  • NSF/ANSI 55
  • NSF/ANSI 58
  • NSF/ANSI 62
  • NSF/ANSI 177
  • NSF/ANSI 244

NSF/ANSI 44: Cation Exchange Water Softeners

NSF/ANSI 44 is a water softener standard. It covers residential cation exchange water softeners, certifying their ability to reduce hardness from public or private water supplies.

This standard encompasses material safety, structural integrity, accuracy of the brine system and the reduction of hardness and specific contaminants from a known quality water source. This includes reductions in barium and radium 226/228 as well as softener performance.

NSF/ANSI 55: Ultraviolet Microbiological Water Treatment Systems

NSF/ANSI 55 is a comprehensive standard for point-of-use/point-of-entry (POU/POE) ultraviolet (UV) water treatment systems. It includes two optional classifications: Class A, dealing with water that is contaminated; and Class B, dealing with water already deemed acceptable by a local health agency.

Class A systems (40 mJ/cm2) are designed to disinfect and/or remove microorganisms, including bacteria and viruses, from contaminated water to a safe level. Class A systems may claim to disinfect water that may be contaminated with pathogenic bacteria, viruses, Cryptosporidium or Giardia.

Class B systems (16 mJ/cm2) are designed for supplemental bactericidal treatment of public or other drinking water already deemed acceptable. Class B systems may claim to reduce normally occurring nuisance microorganisms.

There are currently only 14 companies and 158 products listed as certified to NSF Standard 55, so if a company selling a UV water purifier is not listed at NSF, be suspicious of their claims to efficacy.

NSF ANSI 58 – Reverse Osmosis Drinking Water Treatment Systems

NSF/ANSI 58 lays out the minimum requirements for certification of point-of-use (POU) reverse osmosis systems designed to reduce potential contaminants in public or private drinking water.

This standard encompasses material safety, structural integrity, and claims over reductions in total dissolved solids (TDS) and other potential contaminants. Most commonly, this standard is used for claims over reduction in cysts, hexavalent and trivalent chromium, arsenic, nitrate/nitrite, and cadmium and lead.

NSF/ANSI 62: Drinking Water Distillation Systems

NSF/ANSI 62 lays out standard to certify POU/POE distillation systems, covering material safety, structural integrity, total dissolved solids (TDS) reduction and a product literature review.

This standard also covers contaminant reduction claims including total arsenic, chromium, mercury, nitrate/nitrite and microorganisms from public and private water supplies.

NSF ANSI 177 – Shower Filtration Systems – Aesthetic Effects

This certification is specifically for shower filters that attach directly to the pipe just in front of the showerhead and claim to reduce free available chlorine.

NSF/ANSI 177 also confirms a product’s material safety, structural integrity, and minimum flow performance.

NSF/ANSI 244 – Supplemental Microbiological Water Treatment Systems – Filtration

NSF/ANSI 244 lays out requirements for certification of claims over reduction of bacteria, viruses and cysts in drinking water. The standard establishes minimum requirements for the reduction of microorganisms using mechanical filtration devices for supplemental treatment of microbiologically safe drinking water.

Similar to other standards, NSF/ANSI 244 encompasses material safety and structural integrity. This standard is designed to certify mechanical filtration devices intended for use only on water supplies already deemed microbiologically safe, i.e. water that meets public water system standards. Such systems are, therefore, intended to provide protection against intermittent issues or accidental microbiological contamination of otherwise safe drinking water.

The Water Quality Association (WQA) also offers a certification program to help you find a quality water filtration system. Their Gold Seal Certificate offers reassurance that a water filter system has been made using safe materials and that the claims listed on the packaging are robust. The WQA seal also certifies that a product will hold up under normal usage conditions. This means that if a model that has been WQA certified is stated as removing 98% of lead from your water, then you can have confidence in the fact that it will do exactly as it says.

Some brands to look out for when buying a water filtration system include:

The water filter market is rife with misleading or downright false claims, especially for UV filters. This means you may end up spending a lot of money on an essentially ineffective system that gives you false confidence in the cleanliness of your water supply. Before spending hundreds, if not thousands, of dollars on a water filtration system, it pays to do your research. This can mean poring over performance data and specification sheets and contacting companies if you have questions.

Short on time or already confused? Well, to make things simple, check the ecoHome directory for the best whole home water filtration systems, shower filters, countertop filter systems, and more.

Leigh Matthews

Leigh Matthews, BA Hons, H.Dip. NT, is a health and wellness writer for Gene Food specializing in plant-based nutrition. Read her full bio here.

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