Best Undersink Water Filters

NSF: 42, 53, 58, 401, P473
Price: 208.99 (Amazon)

After getting through our top two factors in choosing an under sink water filter, we wanted to introduce you to our top-rated product. It ticks a lot of boxes, and to be our top choice it had to.

Description

The Aquasana OptimoH2O has impeccable filtering, here are some of the main contaminants it can reduce or remove:

• Lead: 96.6%
• Chlorine: 97.66%
• Arsenic: 97.6%
• Cysts: >99.99%
• Emerging compounds: >94.2%
• PFAS: 96%
• Asbestos: 99%

Performance data sheet

Being tested and certified by the NSF to NSF/ANSI standards 42, 53, 58, 401 + P473 to remove more than 80 contaminants, it is one of the most comprehensively certified systems available. In comparison, more than 50% of under-sink water filters on the market do not have any certifications adhering to NSF standards, and this has 5 of them.

The Aquasana OptimoH20 utilizes a reverse osmosis membrane to reduce 14 impurities, and a patented Claryum filtration method to reduce 60 other contaminants. The filtering process is finished by remineralizing the filtered water with healthy amounts of calcium, magnesium, and potassium, which provides alkaline, pH balanced water. Here is a breakdown of the 3 stages + remineralization:

1. Carbon filtration: Reduces organic chemicals, VOCs and MTBE
2. RO membrane filtration: Filters out dissolved solids smaller than 1 micron including heavy metals.
3. Claryum filtration: Targets chlorine and chloramine (aesthetic issues)
4. Remineralization: Healthy amounts of minerals are absorbed back into the purified water to raise the pH level to a balanced level.

The Aquasana OptimoH20 is also our best under-sink water filter for well water. With over 13 million American households relying on well water for drinking, it’s important to keep the water you drink from your well clean. Well water can have microorganisms such as bacteria, viruses and parasites in it, as well as nitrates, heavy metals, organic chemicals, radionuclides, and fluoride.

Essentially anything that can contaminate water can be in a well water source depending on where you live. So you’ll want to get a powerful filtering system to cover a variety of needs, especially for bacteria, from our research only 29% of under-sink water filters offer bacteria reduction. The Aquasana filters 99% of bacteria, putting it in the top 1%.

The filter life for the Aquasana Optimo is solid with the Carbon and Clayrum filters needing to be replaced every 6 months or 365 gallons, which will cost you ~$65. The RO membrane needs to be changed every 1-2 years according to Aquasana and will cost ~$60, and the remineralizer costs ~$30 and needs changing once a year. If you use less water in your home than you’ll only need to replace the RO membrane once every 2-3 years.

The total system and running cost (filter replacements) for 5 years will cost approximately ~$815, which is an amazing deal considering you are getting the best under-sink water filter on the market.

The system can give you up to 32 gallons per day, to apply this practically, men require about a gallon of water a day, and women require just under 3/4 of a gallon a day according to the Mayo Clinic. So if you take this into account, it can provide enough drinking water for a large family.

Filter life

Look for filters that have to be changed less often. It may not seem like a hassle but if you have to change your under sink filter every 2 or 3 months, it can become irritating, and the risk of banging your head while fiddling around under your sink is real. So, look for filters that only need replacing every 6 months or more.

To ensure this you will want a carbon or sediment filter product with at least 300 gallon filtering capacity as this will typically last up to 6 months.

If you have a reverse osmosis system you will likely have carbon filter replacements that last 6 months, and a reverse osmosis membrane that will need to be replaced annually or can last as long as 5 years in some cases.

For reference, if you are a family of 4 and you each drink the recommended half gallon-gallon of water per day you will consume 60-120 gallons a month, and 360-720 gallons in 6 months.

If you live alone you will consume ¼ of this amount (90-180 gallons). Filters may need to be changed sooner if you consume the amount of water a filter is recommended for, this is to avoid filters becoming clogged with adsorbed contaminants, which leaves no room to capture more.

Price

Compared to other water filters, under-sink products tend to be on the slightly higher end of pricing. They are not nearly as expensive as whole house systems however.

There’s a range of enhanced capability models that are more expensive but low-cost systems usually stick around the $100 threshold.

Under-sink filters that remove chlorine or aesthetic issues will run you about $100.

Higher-quality systems that are certified to remove harmful contaminants such as lead range from $150 to $300. Some premium under-sink filters are on the market for as much as $500, but you don’t need to spend this much for a quality product.

We recommend you stay between the $150 to $300 range, and also look at the ongoing filter replacement costs of your filter, trying to save $50 dollars on a system could cost you hundreds more if it has higher filter replacement costs than another system.

Aquasana coming through with another banger! Okay, we’ll try and contain our excitement a bit, but this system rivals it’s bigger OptimoH2O brother. It has all of the certifications that it does, minus one, which is only for RO systems.

If you don’t want an RO system, then this is a top choice. Certified to NSF/ANSI standards 42, 53, 401, and P473 it has great filtering capabilities.

Description

The Aquasana 2-Stage AQ-5200 system uses Claryum technology in its two-stage filter to eliminate 99% of contaminants that are most commonly found in municipal wells while leaving in essential minerals that are good for you, like calcium and potassium. Here are some of the contaminants that the AQ-5200 can reduce:

• Lead: >99.4%
• Chlorine: 97.66%
• Cysts: >99.99%
• Emerging compounds: >94.2%
• PFAS: 96%
• Asbestos: 99%

Performance data sheet

What really stands out, the Aquasana 2-Stage system has the most certifications we have seen from the NSF for one single under-sink non-RO product. Essentially, you know you’re getting good, pure, and clean water with every drip of the faucet.

Through this system, the water is filtered through an ion-exchange which filters mercury, lead, and other metals while simultaneously preserving the water’s content of minerals so drinkers are still getting potassium, magnesium, and calcium with every glass.

This under-sink filter comes with one set of double filters that provides 600 gallons of purified water at a rate of 10 cents a gallon, significantly less expensive than the price of plastic water bottles sold at stores.

As mentioned before, filtration systems aren’t only saving consumers money but are doing a substantial job at reducing the earth’s carbon footprint.

Once the system starts to beep, the filters need to be replaced. Expect this to happen every six to eight months, depending on the frequency of use.

At $139.99, the Aquasana AQ-5200 comes at a fair price. Its filters cost $59.99 and need to be replaced every six months, which is not extraordinary.

The Aquasana is very small and compact which saves a good amount of space under the sink and can fit in the vast majority of traditional kitchen sinks.

The environmentally-friendly product comes with a one year warranty and retains beneficial minerals like calcium, magnesium, and potassium. It’s easy to install, maintain, and replace and doesn’t typically require any additional help (sorry, plumbers.)

Flow rate, water settings, and unit space

Some people consider flow rate an important factor when purchasing an under-sink water filter. However, most under-sink water filters come with a dedicated faucet that is installed with the system.

Therefore, most under-sink systems will give you a slower running dedicated faucet whilst maintaining the full flow of your existing kitchen faucet. There are some systems that can be installed and don’t require a separate faucet, these are more rare and most will slow down your water flow rate slightly.

Even though flow rate is not the biggest concern when you’re considering an under-sink filtration system, be sure to look for products with at least a minimum flow rate of 0.5 gallons per minute (gpm) for typical under-sink models.

If you want a plumbed in fixture without a dedicated faucet you’ll likely want a faster flow rate, so it doesn’t slow down your faucet every time you turn on your tap. Average water pressure of a faucet is 2.2 gpm, so look for a product rated from 1.5 to 2.5 gpm to avoid your flow rate being noticeably affected.

For Reverse Osmosis systems, their filter rate is slower as they have a more rigorous filtering process. That is why most systems have a holding tank, so filtered water is ready to use right away. We recommended for RO systems you look at gallons per day (gpd), with systems 10 gpd.

PSI is another factor to look for, the majority of under-sink water filters require at least 40 psi water pressure to be effective. The highest psi a house should possibly have is 80 psi, and the average house is 50 psi. So look for a product that can handle between the ranges of 40-80 psi. If your house has low water pressure (<40 psi), then we advise to look for an under-sink filter with a permeate pump, that will boost the water pressure making a filter viable.

In terms of space, if you live in a small apartment, you might want to consider a compact unit of under-sink filters. Obviously, since they’re installed beneath your sink, these types of filters are pretty good when it comes to saving space versus on-top alternatives. If space is limited, even beneath the sink, some countertop models are available. The tape measure will be your best friend here, so measure your space and compare it to product dimensions.

When considering water waste, some reverse osmosis systems have high waste to filtered water ratios. For RO systems, you’ll want to aim for a 3:1 or 1:1 ratio.

Warranty

Having a warranty is a good option to consider when purchasing an under-sink filter. If your product ever turns out to be faulty — which happens — you won’t have to deal with the headaches of finding a new one and manufacturers will provide you with a replacement.

The average warranty for under-sink water filters is 1 year. So we’d recommend purchasing a warranty that is at least one year, and more ideally greater. Generally, the longer the warranty, the more confident in their product manufacturers are.

Installation

While some systems are more difficult to install than others, user-friendly systems that are easy to install might be easier on your state of mind. All of the products listed can be installed by consumers.

Some under-sink filters provide easy-to-follow and step-by-step instructions with the goal of making it as easy as possible to go from store to function as soon as possible. Obviously, if troubles ever persist, you can call a plumber to help your installation (We’ve all been there).

Listed above are the 2 products we believe cover most under-sink water filtering needs. Here are more of our top choices that cover more specific needs:

Our runner up choice is a strong reverse osmosis filter, but falls short of the Aquasana H2Optimo and Aquasana 2-Stage.

The APEC RO-PH90 performance data sheet is not readily available, however, we got in contact with APEC and they provided it upon request. Here are the contaminants it reduces:

• Lead: 96.8%
• Fluoride: 93.8%
• Arsenic: 99%
• Chromium: 99%
• Copper: 98.4%
• Turbidity: 98.7%
• Barium: 98.8%
• Cadmium: 98.3%
• Radium: 98.8%
• Selenium: 97.8%

The WQA has certified this product to NSF/ANSI standard of 58 so you know you are getting a quality under sink water filter that has been through rigorous independent testing. 

This is a 6-stage filtration system, meaning it has 6 different filters. Each stage has its own unique filtering capability: 

1. Sediment filter: removes dust, particles, and rust.
2. Carbon block filter: removes chlorine and chloramine and any associated odor and taste
3. Carbon filter: removes VOCs and other common chemicals
4. Reverse osmosis membrane: filters harmful contaminants including arsenic, lead, fluoride, chromium, radium and more.
5. Coconut shell refining carbon: removes any residual taste from RO tank
6. Calcium carbonate remineralization: increase pH level by adding calcium carbonate mineral back into the water.

That’s a lot of filters! Fortunately these filters can be purchased as a complete set. However, like most RO systems the filters need to be changed at different times, as some filters have shorter lifespans. The shortest is 1 year, and the longest is the RO membrane which lasts 3 to 5 years (depending on use). So you won’t be changing filters often. 

The price for 6 filter replacements is around $150, so it’s a great bang for your buck. The majority of under sink filters/reverse osmosis need filter changes at least once every 6 months, so this system is a step above. 

This system is suitable for houses with water pressure between 40-85 psi. This will cover the vast majority of homes water pressures, the average psi of homes is 50 and the maximum is 80. 

This model has a 4 Gal. storage tank, so when that is full the dedicated faucet flows freely. And the storage tank begins to refill as water is used.  The system can filter 90 GPD. For reference, it is recommended to drink ½ to 1 gallon of water a day per person, so if you have a large family it has you covered (and more). 

For the price of just under $350 this comprehensive system has all your drinking needs covered. The 5 year cost for this system including purchase is approximately ~$900.

Its ongoing costs (filter replacements) are low, so this system will be cheaper than most other under sink/reverse osmosis systems long term. 

The APEC comes with a 1-year warranty and lifetime technical support for peace of mind.

The Flint Michigan water crisis grabbed the world’s attention. Making national and international headlines as a result of aging lead pipes leaching the heavy metal neurotoxin into the water supply of over 100,000 Michigan residents. It showed that in one of the most advanced countries in the world, you can get irreversible damage simply by having a glass of water.

If you want to make sure there is not lead in your drinking water, and this is all that matters to you, then the Brondell Coral will remove 99.7% of lead. It is also certified to reduce over 60 other contaminants. Here are a few:

• Lead: >99.7%
• Chlorine: 98%
• Cysts: 99.99%
• Asbestos: 99.96%

Performance data sheet

It’s certifications include WQA certification to NSF 42 and 53, so it will remove both aesthetic issues as well as harmful contaminants. It also has an NSF 372 certification, which means that the product has been made using “lead-free” materials. It’s certified to the equivalent in Canada with a certification of CSA B483.1.

The filter life for the Brondell Coral  is 1 year or 600 Gal., which is great considering the average filter life for under-sink filters is around 6 months. It has a flow rate of 0.5 gpm which should handle all your drinking needs, in a minute that’s one person’s suggested water intake for an entire day. To filter the water the Brondell Coral has three stages of filtration: 

1. Sediment filter
2. Pre-carbon filter
3. Carbon filter

These filters reduce physical, chemical, and biological contaminants that is system is certified for, including:

• Bad taste and odor
• Heavy metals (e.g., lead and mercury)
• Commercial contaminants (MTBE)
• Herbicides
• Industrial chemicals
• Pesticides
• TDS
• VOCs

The price for this system is very fair, coming in below $150 dollars. Filter replacements will cost you $69.99 (for all three). The total 5 year running cost for the system would cost approximately $430 dollars. That’s a great deal for some of the best lead and chlorine filtration out there. 

This Brondell product is easy to install and has a double O-ring filter seal designed to prevent leaks. It is suitable for all households as it has a maximum psi rating of 100 psi and minimum of 35 psi.

Changing filters is easy with it’s twist and lock design, so no tools are necessary. It even has a filter change reminder, so you won’t have to keep track yourself. The one year warranty included is about average for under-sink filters.

This system has a capacity of 6,000 gallons but it’s known for being the ideal option for customers who don’t want a dedicated faucet. The system is added directly to home’s water line so it’s perfect if you don’t want a dedicated faucet.

It reduces particulate, chlorine taste and odor, lead, parasitic protozoan cysts, and select volatile organic compounds (VOCs) such as benzene and p-Dichlorobenzene. Here are the main contaminants the 3M Aqua-Pure reduces:

• Lead: 99.6%
• Chlorine: 97.4%
• Cysts: >99.99%
• Particulate Class I: 99.4%

The 3M brand has been manufacturing water filtration products for over half a decade and most of their products sport the NSF 42 and 53 certifications. 

Filters are a bit expensive at $120.42 and the overall price is mid-to-high range at $223.52.

Because it doesn’t require a separate faucet, it’s very easy to install but requires some general household tools during setup. Since there’s no need to alter the counter, however, installation can be very quick and cost-efficient.

We understand the importance of using money effectively, especially in the current state of the world where job security is less stable than it ever has been in many of our lifetimes.

The standout point for the Filtrete Maximum is that it costs only $53.99, which is the cheapest option we have found for being able to reduce both Chlorine, Lead, and some other harmful contaminants.

This is a perfect choice if you are looking to affordably target some contaminants and don’t need more brod filtering capabilities. The total five year cost of $400 is the lowest on our list, so not only are you up front costs cheap, but so are the filter replacements. 

This model also has a high flow rate, as it is plumbed directly into your cold water line it is certified to flow at 1.5 gpm, so it will slightly reduce the average flow rate of most homes, which is 2.2 gpm. But you should not notice a significant change. 

Here are some of the main contaminants the Filtrete Maximum reduces:

• Lead: >99.3%
• Chlorine: >97.4%
• Cysts: >99.95%
• Particulate Class I: >99.9%

Performance data sheet

Unlike most point-of-use water filters, under sink systems are less constrained by the need to be small or portable. This means they’re able to employ more rigorous, powerful types of filtration mechanisms, such as reverse osmosis and carbon block filters.