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There are many reasons you might want to filter your drinking water. Likewise, there are many companies looking to sell you a water filter! But how do you tell which ones really work, and which are all marketing nonsense? One way is to pick a NSF Certified water filter, which has been independently tested and approved by NSF International. In this guide, we’ll help you find the best NSF Certified water filter for your needs & budget.

Many of the most-reputable water filter manufacturers will get their products NSF Certified. So, if you’re lost in a sea of too many filter options, looking for an NSF certification is a great place to start.

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Quick Picks for the Best NSF Certified Water Filter of 2021

All-Time Bestseller NSF Certified Filter

Aquasana AQ-RO-3.55 Reverse Osmosis Under Sink Water System Filters 95% of Fluoride-Kitchen Counter Faucet Filtration, 32 Piece Set, Brushed Nickel

  • Drink With Confidence Knowing Your Drinking Water Has Been Purified Through Both Reverse Osmosis & Aqua Sana's Claryum Filtration
  • One Of A Kind High Performance Filter
  • Removes 5x More Contaminants Than Other RO Systems

Culligan FM-15A Faucet-Mount Advanced Water Filter, 200 Gallon, White

  • FEATURES: Reduces azine, chlorine, lindane, lead, particulates class I, turbidity while removing bad taste/odor;
  • Carbon block filtration method; Flow rate of 0.5 gpm at 60 psi; 30-100 psi pressure range; 40-100°F temp range; Easy installation with no tools

iSpring RCC7AK, NSF Certified, 6-Stage Reverse Osmosis System Under Sink, Alkaline Remineralization pH+ RO Water Filter System, 75 GPD Superb Taste Drinking Water Filter

  • 6-Stage Alkaline Remineralization Layered Filtration
  • The iSpring RCC7AK water softener includes an additional sixth stage

Our Research


Our Picks for the Best NSF Certified Water Filters

These selections were made based on a combination of our own testing and research, NSF Certifications, manufacturer specs and third party NSF water filter reviews. Only the best water filters for our readers!


Top Overall: Aquasana OptimH2O

Aquasana OptimH20

Key Features: NSF Certified for 5 different standards; effective reverse osmosis filtering; removes over 85 different harmful contaminants.

Price Range: $$$

The Aquasana OptimH2O system is a reverse-osmosis filter setup that installs under your kitchen sink. We chose it as the best NSF Certified water filter in 2021 because it’s earned several NSF certifications – meeting standards 42, 53, 58, 401 and P473. Most filters are only certified for standard 42 and/or 53, but this unit goes further to effectively filter out a huge variety of potential contaminants.

For complete peace of mind, it’s tough to beat this system. It’s designed to filter out more than 5x the number of contaminants that most reverse osmosis systems cover. Not only is it designed to be a versatile filtration system – it’s actually third-party certified to be just that!

This unit is more pricey than the others on this list, but it’s also more effective. It comes with everything you need, including a holding tank, reverse osmosis filter setup, and even a stylish faucet! It even has a remineralizer; a type of filter that adds healthy minerals back into the filtered water. That’s why the overwhelming majority of Aquasana water filter reviews from customers are very positive.

Overall, this is the best NSF Certified water filter. Click here to buy from Aquasana, or Click here to buy from Amazon.


Budget-Friendly: Culligan FM-15A

Culligan FM-15A

Key Features: Very budget-friendly; NSF 42 and 53 Certified; good flow rate; easy to install

Price Range: $

The Culligan FM-15A is a budget-friendly NSF water filter that attaches directly to your faucet. It features an easy on/off switch that allows for easy access to higher-flow, non-filtered water. It’s certified by NSF to meet standards 53 and 42, and it’s effective in removing a wide range of contaminants. It’s well built, with durable metal and plastic construction.

The affordable replacement filters on the FM-15A are designed to last for 200 gallons of filtered water. So, both the upfront cost and the ongoing costs are quite affordable for this unit. It’s made by a trusted brand, and earns solid reviews from customers.

If you’re looking to stick to a budget, or you just aren’t sure if you need a pricey filter, this is a great option. Learn more here.

High-Capacity: iSpring RCC7AK

Key Features: Very high capacity; NSF Certified; great flow rate; super easy to install

Price Range: $$

The iSpring RCC7AK high capacity water filters remove up to 99% of over 1000 contaminants, such as lead, chlorine, chloramine, endocrine, endocrine disruptors, fluoride, arsenic, asbestos, calcium, sodium, pesticides, heavy metals, herbicides, viruses and bacteria like e-coli and many more.

It includes an additional sixth stage Alkaline Remineralization water filter, that restores minerals and produces a balanced alkalinity, which gives the water a more natural, fresh, and clear taste than regular 5-stage RO certified water.

This water filter has premium quality components that ensure customers’ reliability and low maintenance for the years to come. With easy, do it yourself installation that fits under a standard kitchen sink iSpring RCC7AK is the best NSF water filter that comes with all parts included, and organized step by step instructions and videos.

Cheapest: Brita SAFF

Key Features: Very cheap; NSF Certified; high durability; high capacity

Price Range: $

We present to you one of the cheapest and easy-to-mount water filters – Brita Chrome On Tap Faucet Water Filtration System that filters out impurities for healthier, better-tasting water in a shiny chrome finish. Interested to know what kind of contaminants this water filter removes?

This basic faucet mount removes 99% of lead, reduces chlorine and asbestos contaminants that are found in tap water, also countless other heavy metals and other harsh chemicals. Not only does this water filter work effectively but it’s easy to use, and its space-saving design and small size allow it to be attached easily to the faucet without adding a bulky look on the sink.

One Brita water filter can provide up to 100 gallons of filtered tap water or as we say certified water and includes a built-in filter indicator to signal the need for replacement after approximately 100 gallons or 4 months. This certified NSF water filter is perfect for families and kitchens where meals are cooked and freshwater is needed.

Most Versatile: CuZn UC-200

Water Filter

Key Features: Under counter; NSF Certified; high capacity; made in USA

Price Range: $$

If you have aged water installation and old pipes then this water filter is the best choice that you can make in order to purify your tap water and get the best out of it, because It’s a wide-spectrum under the sink NSF certified water filter that is used for chlorine-treated tap water.

It has an incredible capacity (lifetime) with 5 years per filter, yes guys 5 years and it connects to your kitchen sink’s cold water line plus it is really easy to mount because you’ll only need an adjustable wrench.

The CuZn water filter is a 3 stage filtration system with a micro sediment membrane. Also, it has KDF-55 and Coconut Shell Carbon. The KDF-55 is a way to keep your water safe from harmful chemicals and metals found in your pipes, like lead, mercury, chromium, and other dissolved metals plus it also controls the build-up of bacteria.

Another really great thing is that this water filter purifies your water while it’s not removing all the healthy minerals and what it removes is a range of pollutants including herbicides, pesticides, algae, bad taste, molds, and others all because of the coconut shell carbon filtration that acts bacteriostatic and not responsive to mold or bacteria growth.

Value For Money: Epic Nano Water Filter Pitcher

Epic Water Filter Key Features: LED Filter timer; NSF Certified; 100% BPA Free; made in USA

Price Range: $

This Epic Water Filter is also designed to remove about 99% of all the water contaminants, the water filter is replaceable and tested to the highest industry standards. This NSF certified water filter has a lifespan of 3-4 months depends of your daily use and the quality of your tap water, so if your municipal water is full with contaminants, heavy metals and other pollutants the filter will try to work his job and try to keep your water clean and that will decrease the lifespan of your water filter.

Once you will start using the Epic pure water filter pitcher, within a couple of days you will notice a huge difference in the freshness within yourself and the level of energy that your body has.

So to wrap it up this water pitcher is like BRITA but on a higher and more hardcore level because it is used by preppers and survivalists and plus the BRITA filter supports 40 gallons of water while this water filter can filtrate through like 200 gallons of certified water. The filter elements are 100% BPA free and the filters themselves are 100% recyclable which means that over the lifetime of the water filter, you will save using 1500 plastic water bottles and we can say that that’s a definitive environmental impact.

Easy To Use: ZeroWater ZP-010

Key Features: Stylish; NSF Certified; compact design; super easy to use.

Price Range: $

At home, on the job or on the road as ZeroWater users are saying, this 5 stage filter purifies water in a unique way. It easily filters out 99% of the total dissolved solids.

They have maybe the best portable water filter that is reliable and easy to use. The 5-stage Zero Water filter is able to get more out of your water and this is possible due to the combination of uniquely structured filters and the special ion exchange resin.

For example, the pour through, gravity-fed filter certified by the NSF to reduce lead and other heavy metals, such as Chromium 3 and 6. This 10- cup pitcher features push and pour spout so you can fill your cup with one hand and on top of that you will know when it’s time to change your water filter as every pitcher comes with a water testing meter, which measures the total dissolved solids in your water that makes it one of the best NSF water filters that make certified water taste like natural spring water.

Filtered Pitcher: AquaGear 


Key Features: Above NSF 42 and NSF 53 standards; Advanced 5-stage filter; guaranteed for life; great reviews

Price Range: $$

The AquaGear Water Filter Pitcher is the above NSF standards 42 and 53 for chlorine reduction, lead reduction, and VOCs reduction but please be aware this product isn’t actually officially certified by WQA or NSF International, the two leading independent certifiers. NSF certified water filter, if you prefer the simplicity of a water pitcher style but want it certified an alternative would be the ZeroWater 10-Cup Round Water Filter. This style of filter requires no installation or prior experience to use – you simply fill it with tap water, keep it in your fridge, and enjoy clean, filtered drinking water all day long!

The AquaGear is NSF 53 certified AND NSF 42 certified, meaning that it meets two of the most important standards that NSF regulates. It’s tested for the effective removal of chlorine, chloramines, lead, fluoride, chromium 6, mercury and more. It uses an advanced 5-stage filter that’s effective in removing or reducing a huge range of contaminants.

This is also probably the most affordable NSF 53 water filter out there – although keep in mind the cost of replacement filters. Bottom line, this is a great product and one of the best NSF water filters out there. Click here to learn more about the AquaGear.

What Does NSF Certified Mean?

NSF International is a public health and safety organization that works to improve global human health. They do this primarily by testing and certifying various products. They are heavily involved in food safety testing, water filtration technology certification, and consumer product regulation.

In the context of water filters, NSF Certified means that the product has met or exceeded the NSF Standards for Water Treatment Systems. These are formal guidelines laid out by the NSF. Manufacturers of water filtration systems will send their products to NSF for testing in order to try and earn the NSF Certified seal.

NSF tests for things like:

  • Build quality and durability
  • Use of approved plastics that won’t leach into your water (i.e. no BPA plastics)
  • Verified manufacturer test results
  • Verified manufacturer claims and labels

So, in short, NSF Certified means that an independent, third-party organization has thoroughly tested the product and found it to meet certain guidelines. It’s a stamp of approval, and gives you some peace of mind knowing that the product has actually been evaluated by a reputable third party.

This helps set some of these products apart from the competition. All water filter manufacturers say that their products will remove X, Y and Z, but few of those claims have actually been verified by a reputable third party. When you get a water filter certified by NSF, you’ll know that industry experts that aren’t affiliated with the manufacturer have actually tested the product and confirmed its effectiveness.


What are the Different NSF Standards?

NSF uses a number of different standards to describe filters’ efficacy for various contaminants. Here’s what each standard means:

NSF/ANSI 42 – Filters meeting NSF 42 are certified to reduce aesthetic impurities, such as chlorine and unpleasant tastes/odors.

NSF/ANSI 53 – Filters meeting NSF 53 are certified to reduce one or more contaminants with a known health effect, according to the U.S. EPA. Examples include lead, giardia, VOCs, etc.

NSF/ANSI 44 – Products meeting NSF 44 are certified to help soften water by reducing deposits of magnesium and calcium.

NSF/ANSI 55 – Products meeting NSF 55 are certified to help inactivate viruses, bacteria and cysts through the use of ultraviolet light. This certification has two classes: class A can help kill bacteria and viruses, while class A can reduce non-disease causing bacteria.

NSF/ANSI 58 – Products meeting NSF 58 are certified to help reduce contaminants that are regulated by the EPA and Health Canada. Examples include lead. NSF 58 filters are usually reverse osmosis setups.

NSF/ANSI 401 – Products meeting NSF 401 are certified to help reduce one or more emerging contaminants, which refer to pharmaceuticals or chemicals that are potentially harmful, but are not yet regulated by the FDA or Health Canada.

There are many more NSF standards (full list here), but these are the most common and relevant for home water systems.


What About Other Certifications? WQA vs NSF and Others

The world of international standards and certifications is somewhat complex. Unless you’re directly involved in the industry, you don’t really need to concern yourself with too many of the nitty gritty details. Here’s the basic rundown:

NSF and other product testing/certification organizations such as WQA and others, are all essentially very similar. These are organizations that conduct testing on products from various industries.

All these organizations follow certain government regulations and standards, and are accredited by approved organizations. The two largest ones are American National Standards Institute (ANSI) and the Standards Council of Canada (SCC).

So, when comparing WQA vs NSF, there’s really not much of a difference. Both follow public-domain NSF/ANSI standards when conducting their tests.


Importance of Water Filtration

Taste – Generally speaking, filtered water simply tastes better than unfiltered tap water! Many contaminants can cause an off-putting taste, but some of the most common offenders are chlorine and iron. By using a filter, you can enjoy cleaner, fresher water – which may also inspire you to drink more and stay more hydrated!

Safety – There are some safety concerns associated with drinking unfiltered tap water. For instance, chlorine has been linked to an increased risk of cancer, while fluoride has even been linked to brain damage. Keep in mind that both chlorine and fluoride are routinely added to drinking water. Other contaminants, like lead and mercury, can cause even more grave health concerns. Of course, the safety of your drinking water depends on where you live and other factors – but the bottom line is that drinking filtered water can help minimize the risk of certain health concerns associated with drinking water contaminants.

Peace of Mind – Knowing that you are drinking clean, safe and tasty water can provide significant peace of mind – an invaluable commodity. Even if your water tastes fine and is relatively clean, nothing beats knowing that what you’re drinking is safe and pure.


How We Chose 

NSF Certification Standard – NSF International has several different certification standards. Each means something slightly different, and refers to the specific contaminants that each filter is certified to remove. We picked filters that – at a minimum – satisfied standards 42 and 53. You can learn more about NSF standards here.

Reviews – Beyond the seal of approval from NSF, we also paid close attention to what everyday people thought of these products. Reading third party NSF water filter reviews allowed us to get a broader data set for each product’s effectiveness and durability.

Value – We love helping our readers drink cleaner water – particularly when they don’t have to spend much to do so! We focused on finding excellent products at reasonable prices, that offered great value overall.

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