2024 Home Water Filter Buyer’s Guide + Tips

Heather Dessinger

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Toddler touching water pouring from faucet

Water, agua, amazi << No matter the language it’s described in, water truly is “The Stuff of Life.” It makes up about 60% of our bodies, and is essential for delivering oxygen throughout our bodies, supporting detoxification, lubricating joints, keeping skin supple, and so much more. 

Water purity absolutely matters, but unfortunately it’s been nearly 20 years since the EPA has added any contaminants to the list of chemicals covered under the Safe Water Drinking Act. That means: 

  • Only a tiny fraction of the chemicals in our water supply are monitored and/or regulated in any way, and new chemicals are being introduced all the time
  • Current research challenges the claim that the “acceptable levels” set by the Safe Water Drinking Act for some contaminants are actually safe

The good news is that while regulations have not kept up, some water filtration companies have . . . and many have created affordable options that truly work. 

In this article I’m going to share my process for finding an independently-tested, proven water filtration system that filters “contaminants of emerging concern” alongside other toxic substances like fluoride, pharmaceutical drugs, and radium. 

We’ll dive into: 

  1. How to find out what’s in your water
  2. Choosing what type of filter you want – countertop, under sink, whole house, etc. 
  3. The scoop on water filtration technology
  4. Checking independent certifications
  5. Comparing water filters and choosing the best option for you
Pouring water from faucet into test tube

Step 1: Find Out What’s In Your Water ^

Water filters are not one-size-fits-all. Some families will have higher levels of lead in their tap water, while others will be more concerned about elevated levels of radiological contaminants like uranium and radium. 

And of course, families on well water need to be more vigilant about biological contaminants like cryptosporidium and giardia. 

Fortunately, it’s fairly simple to figure out what’s in your water supply. In this article I cover the top harmful contaminants to be aware of along with info on getting your local water quality report and/or testing if needed. 

Step 2: Choose Your Water Filter Type ^

There are two basic types of water filters – whole house and point-of-use.

Whole house systems filter water as it comes into your home, and point-of-use systems only filter the water in one specific area of the house like your kitchen faucet, shower head, or fridge water dispenser. 

Here’s an overview of the pros/cons of different types: 

Whole house filters remove contaminants as water comes into the home, which means that all water used for bathing, cooking and drinking has been filtered. While there are some good systems out there, in order to keep water pressure levels from dropping too low they have to filter water at a pretty high rate. 

Because water has less contact time with the filtration materials, whole house systems tend to filters fewer contaminants (and smaller amounts of them) than point-of-use systems. There is one company that says their whole house systems remove contaminants so effectively that no additional filtration is needed for drinking water, but those systems are currently sold out.

Countertop water filters are relatively inexpensive and highly portable, making them a great option for families on a budget or who don’t want to install a permanent setup in their home, apartment or rental. Some are attached to the faucet, and others sit next to the faucet and have to be filled manually. 

Although some barely remove more than chlorine, a few countertop filters are very powerful and can handle hard-to-remove toxins like fluoride. 

Under sink filters keep your counter clutter-free, deliver clean water on demand (vs having to wait for it to filter as is the case with many countertop systems), are relatively low-maintenance, pretty affordable, and usually able to remove a much wider range of contaminants than whole house filters.

Shower and tub filters help remove chlorine, VOCs and other contaminants from bathing water. When we shower, the chemicals in our water vaporize faster than the water itself, creating VOC gases that we absorb via our lungs. A similar process happens with bath water, although it’s likely that fewer chemicals are vaporized and more is absorbed directly through the skin. 

Three stage water filter cleaning on white background

Step 3: Get The Scoop On Filtration Technology ^

Now that we’ve covered the different types of filters available, let’s talk about the filtration materials that they use to remove toxins – what works, what doesn’t, and what to avoid. 

Physical Filters (Pre-Filters)

Many filters remove contaminants using multi-stage processes that refine the water until it is as contaminant-free as possible. Usually this process starts with a physical filter (sometimes called a pre-filter) which removes large particles like sediment, rust, and some bacteria. 

Adsorptive Filters

You already know what absorption is – fluid is dissolved into a liquid or solid, like water being absorbed by a paper towel. 

Many filtration materials use a slightly different process called adsorption. Think of it more like a magnet that binds strongly to the surface certain substances, grabbing onto them so that they’re pulled out of the water. 

Some of the most common adsorbing materials are: 

Adsorptive Filter Material #1 – Activated Carbon

Also known as activated charcoal, this filtration medium is highly effective at removing a wide range of contaminants. It’s made by burning natural materials – often hardwood, bamboo or coconut shells – at high temperatures until they transform into adsorbent granules that can be used in whole-form or ground into powder.

The granules contain millions of micropores that grab onto heavy metals, viruses, poisons, certain types of bacteria, and other substances. 

Just two grams of coconut-derived activated charcoal has a larger surface area than an entire football field. (1)

Carbon filters come in several forms, including a solid carbon block (which is great for thoroughly removing contaminants but can slow down flow rate), granular carbon, coconut activated shell carbon (great for removing chlorine), and catalytic carbon (great for removing chloramines). 

Nearly magical as it is, though, activated carbon does have one downside. Although it attracts bacteria to itself, it does not kill it and therefore can become colonized with bacteria. (2) If that happens, the filter that we’re relying on to remove contaminants could actually be adding more to our drinking water. 

Fortunately, there’s a way around that problem – combine it with bacteriostatic (bacteria inhibiting) materials. As we’ll discuss later in this article, there’s an independent certification called NSF-42 which manufacturers can get to show that their filters have antimicrobial (bacteriostatic) properties. 

Adsorptive Filter Material #2 – KDF Media

KDF, which stands for kinetic degradation fluxion, is a type of filtration material made from high-purity copper and zinc granules. It uses a redox reaction (exchange of electrons) to remove chlorine, iron, heavy metals and other contaminants depending on how it’s made. 

KDF is naturally bacteriostatic, which means it inhibits bacteria. 

Adsorptive Filter Material #3 – Bone Char

Bone char is similar to activated carbon, but it has two notable differences: 

  • It’s very good at filtering out a wide range of contaminants including fluoride, while activated carbon is not
  • It’s made by heating animal bones, whereas activated carbon is made by heating plant material

Adsorptive Filter Material #4 -Aluminum Oxide (Activated Alumina)

This is one material I would personally avoid for two reasons: 

  • Although it supposedly helps remove fluoride, it seems to work best on one form (sodium fluoride) and not the other two newer forms that are most often used (fluorosilicic acid and sodium fluorosilicate). (3)
  • As I wrote about in this article, my personal experience with aluminum oxide is that it only removed 24% of fluoride.
  • At least some forms of aluminum oxide filtration use ion exchange, which basically means that you’re replacing whatever contaminant was in your water with aluminum oxide. (4) Some manufacturers say that the form of aluminum oxide is relatively safe, but others disagree.
  • Some of the aluminum oxide used in water filtration is made with nanoparticles (50-100 nm in size), which some research suggests is toxic and likely to build up in our bodies. (5) (6) I reached out to a popular manufacturer of activated alumina filters to ask if they use nano aluminum oxide (50-100 nm in size) and have not heard back yet. I’ll post an update if/when I do. 

Reverse Osmosis

Reverse osmosis (RO) is often considered to be the “gold standard” technology that filters the most contaminants. It works by forcing water through a semi-permeable membrane which prevents large molecules from getting through. 

However, it does have some downsides, such as: 

Storage tanks can harbor bacteria and mold – RO filters generally have a very slow flow rate, so they’re designed to filter water in advance that is stored in a storage tank for instant access. 

Unfortunately, reverse osmosis systems are typically not very good at removing bacteria, and research has found that the holding tanks can become a breeding ground for bacteria and mold if not regularly cleaned and sanitized. (7) 

Personally, I’m not convinced that regular cleaning/sanitizing is enough, so you won’t find filters with under sink holding tanks on this list. I do like the countertop AquaTru, though, which has a clear holding tank that allows you to see inside and is easy to clean. You can read more about it in this article

Reverse osmosis removes beneficial minerals – Some manufacturers offer post-treatment filters that remineralize the water with calcium, magnesium and potassium, but none that I know of also include trace minerals. With the AquaTru, though, you can access the storage tank directly and add both essential and trace minerals. 

Creates wastewater – For every gallon filtered, 1-4 gallons of wastewater is created (the exact amount varies depending on the filter used). This can increase your water bill. 

RO membranes are fragile – If you go with an RO system, make sure to change the pre-filters on time and do any additional maintenance that is recommended. RO membranes can easily become damaged or clogged by dirt and silt if they are not properly removed by pre-filters, which can decrease the effectiveness of the entire system. 

UV Light Filtration

UV filters offer an additional layer of protection for families with well water or those on municipal water that often receive boil notices due to microbial contamination. 

It doesn’t add or remove anything from the water, but it does use ultraviolet light to kill waterborne organisms like bacteria, viruses and cysts that might be present.

UV systems work best when the water is clear so that the microorganisms can’t hide behind loose particles, so it works best with a good pre-filtration system. Also, not all UV lights are strong enough to kill microorganisms with thick cell walls slike cryptosporidium and giardia, so that’s something to consider when shopping for one. 

Step 4: Check Certifications ^

If you want to know that your filter lives up to the manufacturer’s claims, check to see if it’s certified through the American National Standards Institute (ANSI) or NSF International.

These well-respected organizations have created a series of tests to confirm certain claims, such whether or not a filter removes radium or lead to levels that fall below the Environmental Protection Agency’s maximum contaminant level (MCL) requirement. 

One thing  to keep in mind is that if a manufacturer says their product is “tested to NSF standards,” it is not the same thing as being NSF/ANSI certified. 

Certification is an expensive process, and some companies opt instead to pay independent labs to test their products and validate that they meet the standards set out by NSF/ANSI. 

This kind of third-party testing can be totally legitimate, but some companies claim to have independent testing that actually don’t. If you go with a product that is “tested to NSF standards,” I recommend making sure that they post the actual results provided by the independent lab that confirms filter performance. 

Something else to be aware of is that even when a filter is NSF certified, it doesn’t necessarily mean that every claim the manufacturer makes about it has been validated by NSF International. For example, if a filter is NSF certified for Standard 42, that means it has been shown to remove chlorine and contaminants that affect water taste, but not health-related contaminants like barium or bacteria: 

Here’s what to look for: 

  • NSF/ANSI Standard 42 covers aesthetic, non-health-related contaminants such as chlorine
  • NSF/ANSI Standard 44 covers hard mineral reduction, barium reduction, and radium 226/228 reduction, and more
  • NSF/ANSI Standard 53 is mostly for water softeners and covers health-related contaminants such as lead, cysts, and VOCs
  • NSF/ANSI Standard 55 is for UV systems and covers pathogenic bacteria, viruses, cryptosporidium, giardia and non-health-related microorganisms 
  • NSF/ANSI Standard 58  is for reverse osmosis systems and covers total dissolved solids (TDS) plus contaminants such as cysts, barium, copper, arsenic, and lead
  • NSF/ANSI Standard 177 is used to measure the effectiveness of shower filter removal of chlorine

One more important thing to know is that some manufacturers use NSF certified components in their products, but that doesn’t mean the filtration system as a whole has been tested and shown to meet NSF/ANSI standards. 

In the US, the main organization that gives NSF/ANSI certification is the Water Quality Association (WQA). 

Step 5: Compare Water Filters & Choose The Best One For You ^

Whew, you’re finally to the last step – choosing your filter. Now that you’ve done all the groundwork, the process is pretty simple. 

  • Make a final decision on what type of filter you want – countertop, under sink, whole house, shower, or a combination of these. 
  • Hop over to my review of each type of filter and find one that looks good to you (links below)
  • If you have more than one filter you’re interested in, consider factors like initial cost and replacement filter cost and ease of installation. Go to the manufacturers website and check the third-party testing results to make sure it removes the contaminants that are the biggest concerns for you based on your local water quality report.
  • Make your choice based on your needs and budget. 

Ready to get started? ^

Do you have a question I didn’t cover in this article? Please leave it in the comments below!

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1. Dillon, Edward C  et. al. (1989) Large surface area activated charcoal and the inhibition of aspirin absorption

2. Jeffrey A. Trogolo (2011) Activated Carbon: Modern Advances for an Ancient Technology

3. Centers for Disease Control (CDC) Water Fluoridation Additives

4. Duan, Ying (2014) Fluoride adsorption properties of three modified forms of activated alumina in drinking water

5. Shivaprasad, Parimala et. al. (2018) Nano-Structures & Nano-Objects

6. Park, Eun-Jung (2015) Biodistribution and toxicity of spherical aluminum oxide nanoparticles

7. Se-keun Park and Jiang Yong Hu (2010) Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality

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Heather is a holistic health educator, herbalist, DIYer, Lyme and mold warrior. Since founding Mommypotamus.com in 2009, Heather has been taking complicated health research and making it easy to understand. She shares tested natural recipes and herbal remedies with millions of naturally minded mamas around the world.