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2018’s Best Under Counter Water Filtration System Reviews

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    There are so many advantages to high quality under sink water filter systems. For one, they are effective at removing a wide range of potentially harmful contaminants. Secondly, they are affordable, easy to install and maintain – filters usually last a long time – and convenient to use. Basically, you get clean and great tasting water straight from the tap whenever you need it.

    Above that, under sink filters don’t take up any space on your kitchen counter (who would have guessed) and most only little space underneath it, which is great if you have a small kitchen.

    The only problem: How do you find the best under sink water filter for your needs? After all, you don’t want to waste your money on a substandard product, do you? Well, you came to the right place!

    On This Page You Will…

    Undersink Water Filter Comparison

    ModelOur RatingPriceTech/MediaFilter StagesExtra Faucet
    Home Master TMAFC-ERP Artesian Full Contact Undersink System

    Best Rated Under Sink System: Home Master TMAFC-ERP

    badge best rated no stroke

    stars new


    Read Review
    $$$Reverse Osmosis7Yes
    APEC ESSENCE ROES-50 Undersink System

    Best Price-Performance Ratio: APEC ESSENCE ROES-50

    best price

    412star new


    Read Review
    $$Reverse Osmosis5Yes
    Woder 10K-Gen3 Undersink System

    Best Seller: Woder 10K-Gen3

    badge best seller

    stars new


    Read Review
    $Carbon Filtration1No
    CuZn UC-200 Undersink System

    Highest Filtration Capacity: CuZn UC-200

    stars new


    Read Review
    $Carbon Filtration+ Oxidation3No
    Ecosoft 3-Stage Undersink System

    Cheapest Multi-Stage Under Sink System: Ecosoft

    4 and a half stars


    Read Review
    $Carbon Filtration + Special Media3Yes
    BACOENG UF Undersink System

    No Green Light for: BACOENG UF System

    212stars

    $Ultrafiltration4Yes

    What You Need to Consider

    You have many, many options when it comes to choosing a water filter system to install under your kitchen counter. In order for you to find a unit that’s best suited to your needs, here is what you should consider:

    1. NSF Certifications

    Almost all water filters do a great job at reducing chlorine and improving overall water aesthetics, which is a good start. But what about the really bad stuff, say lead and pesticides for example?

    Truth is, not all water filters are created equal. Some are more effective at removing certain kinds of contaminants than others, which is why there are huge differences in the level of water purity they can provide.

    By checking for important NSF certifications, you can make sure that a certain filter or system is able to remove all or at least the majority of harmful substances your water tested positive for. What certifications to focus on? Standard 42, 53, 401 and 58 (reverse osmosis systems only).

    2. Filter Technology

    There is carbon filtration, there is reverse osmosis, there is ion exchange. Different filter systems use different technologies and media to help you get rid of impurities in your water. And while reverse osmosis delivers the best possible results, it might be sufficient for your water conditions to install a filter that’s much more simple.

    Usually, the best approach is to have your water tested as a first step. As soon as you know what you are facing, you can go out and find an appropriate filter.

    As an aside, Total Dissolved Solids (TDS) is not a good measure for testing water quality. Except for RO systems, most under sink water filters won’t even reduce TDS, which is not necessarily a bad thing. You have to know that TDS also includes healthy minerals – think calcium – that occur naturally in water.

    3. Filter Stages

    Although there are exceptions, the general rule is that the more filter stages a system has, the higher the quality of water that it will provide.

    The downside is that the more stages, the higher the costs for maintenance and the bulkier the system.

    4. Flow Rate

    Non-RO under sink systems don’t come with a storage tank. So the water gets filtered on demand. The thing is, nothing is more annoying than having to wait hours to fill a single glass of water #exaggerate. But seriously, pay attention to water flow rates measured in gallons per minute (gpm).

    As you probably know, a standard kitchen faucet that has no filter attached to it delivers somewhere around 2.0 gpm. The lowest flow rate we could find with an under sink system was 0.25 gpm.

    At the same time, you should note that thorough filtration requires time. This is why the Aquasana AQ-5300 for example, which features a very sophisticated purification process, provides no more than 0.5 gallons of filtered water per minute.

    flow rate

    5. Installation

    When you can actually install a water filter system yourself, you save quite a bit of money by not having to call a plumber. The good news is that most under sink purifiers fall under this category – even if you don’t have any prior experience. Some don’t even require the use of tools, except maybe for an adjustable wrench to tighten the fixings.

    If a systems comes with a dedicated faucet rather than featuring an in-line design, the installation can be more difficult, but not too much. You will have to drill an extra hole somewhere in your counter in case your kitchen sink doesn’t have a spare one.

    By the way, the advantage of using a dedicated faucet is that you don’t have to purify every single drop of water that you use. Only water used for direct consumption gets filtered. This will help you to save time and money in the long run. How? It’s simple: Your filters are going to last much, much longer. On the other hand, if all the water is being processed, the filters will reach their capacity a lot sooner.

    6. Maintenance & Filtration Capacity

    Apropos capacity: One of the greatest benefits of under sink filter units is that they are low in maintenance, so less for you to worry about. The reason for this is that the amount of gallons that a single filter cartridge can handle before it needs replacement is relatively high. For example:

    One of the filters we reviewed down below has a capacity of 50,000 gallons. If your family uses 3 gallons of filtered water per day, 50,000 gallons will last you for more than 45 years – at least in theory. Because filters are also limited by how long you can use them. This is due to the fact that bacteria might grow inside the filter media after months or years of use.

    Also, remember that filtration capacities are ideal values. Depending on the conditions in your home, such as feed water quality, a filter might never actually reach that benchmark.

    The amount of work that is required to maintain a water filter system also depends on how well it was designed. Twist on/off filters can be changed in under 2 minutes. Filters with housings can be a pain in the a**.

    7. Size

    Some under counter water filters are larger than you’d think. If you have unlimited space in your sink cabinet, this doesn’t really matter. However, if you don’t, this should influence your final buying decision.

    Also, don’t forget that reverse osmosis systems use an extra storage tank.

    8. Costs

    In terms of costs, you have to take into account the initial purchase price plus recurring costs for replacement cartridges, which start to add up over time. This is when high filtration capacities with fewer changes really pay off.

    In all our reviews, we also estimated annual filter replacement costs for each system.

    Reverse Osmosis Under Sink Systems

    If you are looking for the best reverse osmosis under sink system, here are our top recommendations:

    Home Master TMAFC-ERP Artesian Full Contact Undersink System

    Best Rated Under Sink System: Home Master TMAFC-ERP

    Read Our Review

    •    Price: $$$
    •    Filter Stages: 7
    •    Tech/Media: RO
    •    NSF Standard: 42
    •    Annual Costs: ~$85.00
    •    Extra Faucet:
    APEC ESSENCE ROES-50 Undersink System

    Best Price-Performance Ratio: APEC ESSENCE ROES-50

    Read Our Review

    •    Price: $$
    •    Filter Stages: 5
    •    Tech/Media: RO
    •    NSF Standard:
    •    Annual Costs: ~$75.00
    •    Extra Faucet:
    Olympia Water Systems OROS-50 Undersink System

    Cheapest RO Under Sink System: Olympia OROS-50

    Read Our Review

    •    Price: $
    •    Filter Stages: 5
    •    Tech/Media: RO
    •    NSF Standard: 42, 58
    •    Annual Costs: ~$70.00
    •    Extra Faucet:

    In a Nutshell:

    1. The Home Master TMAFC-ERP provides the purest water of all, thus making it the best under counter water filter. The system is made in the USA, backed by a 5-year warranty and comes with a permeate pump to reduce the amount of wastewater that goes down the drain by up to 80% – a real money saver!
    2. APEC’s ESSENCE ROES-50 has the best price-performance ratio. 5 stages of filtration help you to get rid of lead, fluoride, arsenic and lots of other nasty stuff. The unit always is one of the best sellers on Amazon.
    3. The Olympia Water Systems OROS-50 is one of the most affordable RO systems while still providing quality filtration. It has even earned NSF standards 42 and 58 certifications, which is a great start!

    For even more RO systems, click here to get to our main reviews page.

    Woder 10K-Gen3 & Woder 10K-DC

    Woder 10K-Gen3 Undersink

    Best Seller: Woder 10K-Gen3

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42
    •    Annual Costs: ~$16.00
    •    Extra Faucet:
    Woder 10K-DC Undersink

    Woder 10K-DC

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42
    •    Annual Costs: ~$24.00
    •    Extra Faucet:

    What We Like

    The Woder 10K-Gen3 and the Woder 10K-DC are among the best selling under sink water filtration systems on Amazon.

    Both use the same activated carbon filter media, they are compact in size, and as their names suggest their filtration capacity is about 10,000 gallons or a minimum of 3 years when used on city water. This is about 3 times as much as what you get with most other filter systems.

    However, bear in mind that if your water contains a lot of hardness minerals or if it was processed by a softener before, the actual number of gallons might be lower.

    The only difference between the two systems is that the Woder 10K-DC (which is a bit cheaper) must be replaced as a whole. The Gen3 on the other hand features a smart head with a built-in valve, which allows for changing the cartridge only.

    In other words, if you use the Gen3 for long enough you will benefit from the smart head and save some money further down the road. By the way, replacement costs are super low.

    Also, both system are made with NSF 42-approved materials and can also be used in RVs.

    What contaminants are removed?

    • 99.9% lead*
    • 99.9% chromium-6*
    • Other heavy metals
    • 99.9% chlorine*
    • VOCs
    • Turbidity
    • Bad tastes and odors

    *as per independent lab tests

    Looks like from now on you can enjoy healthy and great-tasting drinking water right from the tap!

    As far as the installation is concerned, both units come with everything you need in order to set them up within minutes – literally. No expert skills required.

    All you need to do is turn off the water supply under your sink, disconnect the cold water line and then attach the systems’ inbound and outbound hoses (3/8″ by 1/4″). That’s it!

    What We Don’t Like

    There are 2 aspects that we don’t like:

    1. The seller claims that the provided water flow rate is 2 gpm. However, the filter itself is rated at 0.8 gpm. All in all, it would be nice to have a slightly faster flow rate.
    2. We miss additional NSF certifications.

    Our Verdict

    What you want is unlimited access to refreshing and clean drinking water? The Woder 10K-Gen3/DC can give you that.

    The units come at a great price and are backed by hundreds of positive customer ratings. Did we mention Woder’s “YOU’LL LOVE IT”-guarantee? Either you love what you get or you send it back and receive a full refund. What are you waiting for? Go check it out!

    CuZn UC-200 Review

    CuZn UC-200 Undersink System

    Highest Filtration Capacity: CuZn UC-200

    •    Price: $
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 61
    •    Annual Costs: ~$24.00
    •    Extra Faucet:

    What We Like

    A couple of things make the CuZn UC-200 inline water filter stand out:

    • It’s manufactured in the USA – which is quite rare nowadays.
    • It’s bacteriostatic – meaning that there’s almost no chance that bacteria or mold will grow inside the unit. This is a great benefit over regular carbon filters.
    • No maintenance required – simply set up the system and forget about it for the next couple of years.
    • It’s one of the top rated under counter systems on the market.

    Speaking of maintenance, theoretically, you get a filtration capacity of 50,000 gallons or an equivalent of 5 years, whichever comes first.

    Why theoretically? Because it always depends on feed water quality. Just like most other under sink filter systems, the CuZn UC-200 cannot handle hard water very well – one of the reasons to not use it on well water.

    Once the filter has reached its capacity you have to replace the entire unit.

    What about the filtration process? It’s 3-stage combining micro sediment membranes and different filter media and everything is NSF certified against Standard 42 and/or 61.

    It’s time to finally say goodbye to a range of organic and inorganic contaminants, such as chlorine, lead, mercury, herbicides, pesticides among others (not fluoride, sorry).

    If You Want to Remove Fluoride From Your Water, Check Out Our Fluoride Special: best-osmosis-systems.com/water-filter-fluoride-removal/

    And although the system also removes unpleasant tastes and odors, essential minerals like calcium and magnesium are left untouched. This is good for your health, but bad for your coffee maker.

    Furthermore, installing the system is a breeze and will only take you a few minutes. If you don’t know how, CuZn provides a video with step-by-step instructions on their website.

    3/8″ fittings are included. For non-standard plumbing, CuZn usually sends a special installation kit for free, so make sure to reach out to them.

    Lastly, a 5-year warranty and a 90-day satisfaction guarantee are part of the deal, so if you don’t like how the filter performs, just send it back and get a full refund.

    What We Don’t Like

    Some customers had to struggle with leaks, for example at the case of the unit. We also read about black grains that someone found in his water.

    The good news is that CuZn’s customer service is extremely responsive and helpful. The team is willing to take on any problem that users might have with the filter.

    Our Verdict

    Water is supposed to taste like nothing. If that’s what you are looking for and your water doesn’t contain certain contaminants that the CuZn UC-200 can’t handle, definitely give it a shot. You can’t really go wrong. Remember: If you don’t like what you receive, claim the guarantee.

    Aquasana AQ-5300 & Aquasana AQ-5300+ Max Flow

    Aquasana AQ-5300

    Aquasana AQ-5300

    •    Price: $$
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42,53,401...
    •    Annual Costs: ~$130.00
    •    Extra Faucet:
    Aquasana AQ-5300+ Max Flow

    Aquasana AQ-5300+ Max Flow

    •    Price: $$
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42,53,401...
    •    Annual Costs: ~$160.00
    •    Extra Faucet:

    What We Like

    Up next we have 2 under sink water filter systems by Aquasana which are quite similar, namely the AQ-5300 and the AQ-5300+ Max Flow.

    The latter provides 0.72 gallons of water per minute, about 30% more than what you get with the regular AQ-5300 (0.5 gpm). We know, 0.72 gpm doesn’t sound like much. But keep in mind that the more thorough the filtration, the lower the water flow is usually going to be.

    Other than that, the AQ-5300 is more compact in size with lower initial costs. Also, replacement filters are more affordable.

    Both systems feature a 3-stage purification process. Capacity? Between 600 to 800 gallons:

    • Stage 1 uses a 20-micron pre-filter to remove sediment, silt and rust.
    • At stage 2, activated carbon reduces mainly chlorine (>97%) for improved water aesthetics, but also pharmaceuticals, herbicides, pesticides, VOCs and other organic chemicals.
    • Stage 3 uses catalytic carbon media to eliminate chloramine (>97%), which more and more utilities use for water disinfection today. In addition to that, many other dangerous pollutants like lead, mercury, asbestos and chlorine-resistant cysts are filtered out.

    In total, 77 different impurities can be tackled. NSF certifications for Standards 42, 401, 53 and P473 guarantee filtration performance way above standards for exceptionally pure drinking water for you and your family.

    What’s more, the install is relatively simple and can be compared to setting up an RO system. You will have to connect the extra faucet – choose between brushed nickel, chrome and oil-rubbed bronze to match your kitchen decor – but there’s no need to install a drain hose. Of course, all required bits and pieces are part of the package and instructions are very clear.

    Above that, replacing filters about every 6 months or so can be done in no time and without the need to disconnect any water lines. Simply give the filters a quarter turn to twist them off and attach new cartridges the same way.

    On a side note: An indicator light and an alarm sound will let you know when it’s time for the replacement, so no more guess work!

    Last but not least, the AQ-5300 and AQ-5300+ are backed by a 90-day satisfaction guarantee as well as Aquasana’s superb customer service.

    What We Don’t Like

    What we don’t like is that leaks seem to be an issue every now and then. The cause could be a leaky pre-filter, a faulty seal in the housing or a hose that blows off.

    We also think that the push fittings could do with an upgrade.

    Our Verdict

    Aquasana is known for building water purification systems with great filtration performance. This , too, is the case for both the Aquasana AQ-5300 and the Aquasana AQ-5300+ Max Flow. So if you want a water purifier that can provide you with exceptionally clean and delicious drinking water right from the tap, these are your ideal candidates.

    APEC WFS-1000

    APEC WFS-1000

    APEC WFS-1000

    •    Price: $$
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard:
    •    Annual Costs: ~$45.00
    •    Extra Faucet:

    What We Like

    Assembled in the USA, the APEC WFS-1000 under sink water filtration system can be used to treat tap or properly disinfected well water.

    We have 3 stages of filtration that help you to get rid of dust, particles, chlorine, tastes, odors, volatile organic compounds and other chemicals.

    However, for fluoride and heavy metals you will have to opt for a different model, as the WFS-1000 won’t even touch these.

    Most essential minerals are also kept in the water, which is a real advantage as it adds to your daily nutritional intake.

    The flow rate is good and everything is pretty simple to set up, although directions can be a little confusing at first. Still, even if you’ve never done any type of plumbing before, there’s no reason to worry thanks to the quick connect fittings and standard-sized tubing.

    What about replacement filters? Made in the USA and last for about 12 months before they need changing, which is nice because that means less maintenance work for you.

    Speaking of replacement filters, by default filter stages 2 and 3 are identical, which is why you might want to consider using a different cartridge for the latter. Just make sure that it’s standard-sized (10″) and you are good to go.

    One of your options is a specialized fluoride filter. Others tackle chloramine, arsenic or nitrate.

    You also get a stainless steel faucet rather than a cheap one made from plastic and a 1-year satisfaction guarantee plus lifetime California-based support.

    What We Don’t Like

    For more severe cases of water contamination, this under sink water purifier won’t suffice. We are also missing NSF certifications for contaminant reduction rates.

    Our Verdict

    If all your water needs is a finishing touch, by all means go for the APEC WFS-1000. It does what it says and because everything is standard-sized, you can choose from a wide range of cheap replacement filters.

    Culligan US-EZ-1, US-EZ-3 & US-EZ-4

    Culligan US-EZ-1

    Culligan US-EZ-1 for Basic Filtration

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42
    •    Annual Costs: ~$15.00
    •    Extra Faucet:
    Culligan US-EZ-3

    Culligan US-EZ-3 for Advanced Filtration

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53
    •    Annual Costs: ~$48.00
    •    Extra Faucet:
    Culligan US-EZ-4

    Culligan US-EZ-4 for Premium Filtration

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53
    •    Annual Costs: ~$100.00
    •    Extra Faucet:

    What We Like

    Culligan provides a carbon-based under counter water purification system with a dedicated faucet that can be used with 3 different and interchangeable filtration cartridges: The RC-EZ-1, the RC-EZ-3 and the RC-EZ-4.

    • Being the most popular, the RC-EZ-1 is a basic water filter with a maximum capacity of – believe it or not – 3,000 gallons or up to 12 months use. It is NSF Standard 42 certified to reduce chlorine (97.4%), particulates (99.9%) as well as bad taste and odors. In other words, opt for this filter if all you care about is better tasting water and don’t want anything fancy.
    • For higher filtration needs, the RC-EZ-3 removes chlorine and particulates and in addition to that cysts (99.9%), turbidity (98.5%), lead (about 99.0%), atrazine (94.1%) and lindane (98.2%) – all according to NSF Standard 53. Filtration capacity is 500 gallons or 6 months.
    • If you also need to eliminate chloramines, MTBE, mercury, chloroform and dozens of VOCs for increased water safety, the RC-EZ-4 is your best bet. Filtration capacity: 500 gallons or 6 months.

    Quick connect fittings and detailed DIY instructions make installing this unit a breeze with no need for calling a plumber. Above that, twist on/off filters were designed for convenience and can be replaced in mere minutes and without turning off the feed water supply.

    Everything is backed by a 2-year limited manufacturer warranty and great customer service.

    What We Don’t Like

    With .5 gallons per minute at 60 psi, water flow is a little low. Also, the included faucet is made from cheap plastic except for its metal spout, so it’s nothing mind blowing.

    Furthermore, the installation kit comes with a 1/2″ water hose adapter. However, if your house has 3/8″ supply lines, it won’t fit. In this case, you will have to make an extra trip to your local hardware store.

    Last but not least, for the US-EZ-4 premium filter annual replacement costs are comparatively high.

    Our Verdict

    Here you get a low-cost water filter which is easy to set up, low in maintenance and can even be used to overcome lead contamination. It’s perfect for people on a tight budget.

    Ecosoft 3-Stage

    Ecosoft 3-Stage Undersink System

    Cheapest Multi-Stage Under Sink System: Ecosoft

    •    Price: $
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard:
    •    Annual Costs: ~$55.00
    •    Extra Faucet:

    What We Like

    Let’s make this quick:

    The beautiful and sturdy Ecosoft 3-Stage is available for a fraction of the price of other multi-stage purification systems and removes up to 99% of harmful impurities for drinking water that not only tastes great, but also benefits your health.

    • Stage 1 – A 5-micron polypropylene sediment filter traps dust, sand and other sediments and thereby prolongs the life of the subsequent filters.
    • Stage 2 – A mix of a carbon/softening filter reduces water hardness and some of the bad stuff that might be lurking in your water, such as chlorine and chlorination by-products, tannins, and a number of heavy metals including lead, iron, manganese and aluminum.
    • Stage 3 – An activated carbon block removes any residual tastes and odors for a final polish.

    Everything is manufactured in good ol’ Germany and partly in the Ukraine. A faucet + installation kit are included in the package and so is a 30-day satisfaction guarantee, a 1-year full warranty and a 5-year limited warranty. Ecosoft’s customer service responds promptly and is super helpful.

    Replacement filters are reasonably priced. Capacity: 400 gal.

    What We Don’t Like

    .25 gallons per minute is really not a lot of water, so expect longer waiting times.

    On top of that, the installation instructions could be more precise and some of the valves and fittings feel a little cheap. They’ve caused leakages for some users in the past.

    Our Verdict

    All in all, the Ecosoft 3-stage under sink system combines decent filtration performance with a low price tag and negligible maintenance costs. We love it!

    Nahla Pure DC Sink Filter MAX

    Nahla Pure DC Sink Filter MAX

    Nahla Pure DC Sink Filter MAX

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard:
    •    Annual Costs: ~$27.00
    •    Extra Faucet:

    “If only there was a way to turn municipal water into great tasting, pure water…” is how Nahla Pure promotes its DC Sink Filter MAX. Sounds like they’ve discovered a new filtration method. Let’s find out!

    What We Like

    First of all, we are talking about a compact single-stage unit, which has the advantage that it removes all the clutter from your kitchen sink cabinet.

    The filtration capacity is 10,000 gallons of city water (maximum of 3 years use), so you don’t have to worry much about the hassle and costs that come with frequent filter changes.

    The filter itself is made in the USA and uses nothing but NSF-certified materials to remove up to 99.99% of impurities including VOCs, chlorine, lead and other heavy metals. The activated carbon will also make your water taste much better and the antimicrobial silver mixed into the filter media inhibits bacterial growth for additional protection of your family’s health.

    As far as the installation goes, it’s easy and straightforward. The average person should be able to complete the whole process in about 15 to 25 minutes. All you need is a screwdriver and an adjustable wrench.

    Finally, the seller offers a 100% money back satisfaction guarantee. For how long? We do not know!

    What We Don’t Like

    The biggest issue that we see with the DC Sink Filter MAX is that a handful of customers reported that it doesn’t last anywhere close to 10,000 gallons or 3 years of use. Some had to change the filter after about 3 to 4 months, others after 7. If that’s the case for you, too, costs will be much higher obviously.

    Another disadvantage is that the seller does not provide additional details about contaminant reduction rates.

    Our Verdict

    Suited for basic purification needs? Yes. The best under counter water filter in direct comparison? Definitely not. If you require a more thorough filtration, we recommend you to check out some of our other under sink water filter reviews such as this one.

    3M Filtrete 3US Filters

    3M Filtrete Advanced 3US-PS01

    3M Filtrete Advanced 3US-PS01

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53
    •    Annual Costs: ~$76.00
    •    Extra Faucet:
    3M Filtrete Maximum 3US-MAX-S01

    3M Filtrete Maximum 3US-MAX-S01

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53
    •    Annual Costs: ~$70.00
    •    Extra Faucet:

    What We Like

    The 3M Filtrete 3US comes with three interchangeable inline filter variations:

    1. The Standard 3US-AS01 – not really interesting for us, as it filters nothing but particles down to 5 microns – think sand and rust – plus chlorine taste and odor. The filter will last for about 6 months and is NSF Standard 42 certified.
    2. The Advanced 3US-PS01 – filters all impurities down to 0.5 microns including 99.99% of microbial cysts plus all of the above. Again, the filter lifespan is 6 months or 2,000 gallons whichever comes first. Apart from NSF Standard 42, this filter has also earned a Standard 53 certification.
    3. The Maximum 3US-MAX-S01 – The maximum filtration level stands out as it removes 99% of all lead in addition to all the impurities we’ve already mentioned.
      • Micron rating: 0.5
      • NSF certifications: Standard 42 & 53
      • Filtration capacity: Up to 6 months

    For the install, there’s no need to set up an extra faucet. The system will easily connect to your already existing one in less than 30 minutes.

    Also, replacement filters can be changed with a single twist in a matter of seconds – 100% hassle-free!

    What We Don’t Like

    Here are the two aspects that we don’t like:

    1. Even with a new filter cartridge, your flow rate is likely to fall off quickly.
    2. In rare cases, replacement filters have small cracks that will cause water to spray everywhere. You better double check them before the install.

    Our Verdict

    Most customers love this filter system. It’s easy to install and will make your water taste, smell and look so much better.

    However, it won’t stop everything from entering your glass, so if your city water contains pollutants that pose a serious health threat, first find out if one of 3M’s Filtrete filters is up for the job!

    3M Filtrete 4US-MAXL-S01

    3M Filtrete 4US-MAXL-S01

    3M Filtrete 4US-MAXL-S01

    •    Price: $
    •    Filter Stages: 1
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53, 401
    •    Annual Costs: ~$40.00
    •    Extra Faucet:

    What We Like

    3M’s Filtrete 4US-MAXL-S01 is not much different from the 3US filters we reviewed above.

    This under sink filter, too, is rated at .5 microns and can provide purified water for up to 6 months. Watch out: Filtration capacity at 750 gallons!

    The maximum PLUS level filtration removes all larger particles, eliminates chlorine taste and odor, and most importantly reduces select herbicides, pesticides and pharmaceuticals. On top of that, it traps lead and cysts.

    Everything was tested and certified against NSF International standards 42, 53 and 401 (emerging contaminants) for guaranteed drinking water safety.

    The system’s setup is a tad more complicated due to the dedicated faucet.

    For maintenance on the other hand, all you need to do is change filters as soon as you see a drop in water flow or quality. Give the old cartridge a quarter turn to take it out, insert a new one the same way – no tools required. Costs are super low: About $40 per year.

    What We Don’t Like

    3M ships a cheap plastic t-fitting that could be used to connect the system to the cold water line under your counter.

    We definitely recommend you to use a brass fitting instead for improved sturdiness and in order to prevent any leakages. Don’t worry, this won’t cost you more than 10 bucks.

    And in case you receive a broken filter, don’t hesitate to contact 3M’s customer service. The people there are very helpful and will send you a replacement piece free of charge.

    Our Verdict

    If you ask us, this is a product with a good price-performance ratio. Compared to many other single-stage under sink systems the 3M Filtrete 4US-MAXL-S01 is slightly more expensive, but also does a better job at providing high-purity water to meet strict NSF standards for a wide range of impurities.

    Brondell H2O+ Coral UC300 Multi-Stage Unit

    Brondell H2O+ Coral UC300

    Brondell H2O+ Coral UC300

    •    Price: $$
    •    Filter Stages: 3
    •    Tech/Media: Carbon Filt.
    •    NSF Standard: 42, 53, 372
    •    Annual Costs: ~$90.00
    •    Extra Faucet:

    What We Like

    The last of our under sink water filter system reviews features the Brondell H2O+ Coral UC 300. It’s a 3-stage unit that has earned certifications for NSF standards

    • 42 for water aesthetics (chlorine, tastes, odors, particulates and even 98.6% chloramine),
    • 53 for water contaminants with health effects (cysts, mercury, lead, VOCs, TTHMs, …)
    • and 372 for product compliance with lead content.

    Above that, a certification for Canadian water filtration standards has been awarded. Altogether, this system gives you access to water of unusual high purity.

    A word on chloramine:

    Chloramine is a substance that is increasingly used in public water system for disinfection purposes a.k.a. killing bacteria and viruses. According to the CDC, already back in 1998 about 70 million Americans received drinking water that had been treated with the chemical.

    The bad news is that in many cases chloramine-treated water contains higher concentrations of currently unregulated disinfection byproducts that may be toxic. Also, monochloramine enhances metal corrosion, which increases the chance for lead to enter our water supplies.

    Want to learn more about the topic? Our BOS guide on chlorine/chloramine removal provides you with everything you need to know.

    Back to the Brondell H2O+ Coral. Here are some details about its filters:

    • Stage 1 applies a regular sediment pre-filter, while stage 2 and 3 utilize carbon media.
    • The filtration capacity is 600 gallons or 12 months, which is above average and will help you to save money in the long run.
    • Water flow is 0.5 gallons per minute, which is okay. You might have to wait a little longer to fill a whole jug, however, remember that thorough filtration requires time.
    • The twist and seal design makes filter changes quick and easy.
    • The chrome faucet even has an integrated LED light that indicates when it’s time to change filters – a handy feature that takes out all the guess work.

    Lastly, a one-year limited warranty got you covered in case something goes wrong.

    What We Don’t Like

    Basically, the idea is that everything you need to set up this system right away should be included in the package. This way you don’t have to pay a visit to the hardware store, which makes a lot of sense.

    However, the 1/2″ to 3/8″ adapters have bad threading and might not tighten onto your water supply line properly. So chances are that you will still have to buy a replacement piece nonetheless or otherwise your kitchen will be flooded.

    Our Verdict

    An under sink filter system perfectly suited for water treated with chloramine and yet some room for improvement. Once you have everything in place, we are 100% sure that you will be happy with this purchase.

    More on Under Counter Water Filter Systems

    In the first section, we reviewed some the best under sink water filter systems on the market. Next, we are going to answer 2 of the most common questions our readers have regarding this special type of filter.

    How to Install an Under Sink Water Purifier

    Installing a water filter under the sink is not difficult at all – we promise. Chances are good that even without any prior plumbing experience you can do everything DIY style. So hopefully spending any money for calling a plumber won’t be necessary.

    But even if you do hire a professional, he shouldn’t need more than 30 minutes to set everything up, so costs should be reasonable.

    Now, the level of difficulty depends on what kind of system you’ve purchased. Many single-stage units feature an inline design, which means that they directly connect to your already existing sink faucet – it doesn’t get any easier than that.

    The majority of multi-stage systems, however, come with an extra faucet that might require you to do some drilling. This depends on whether or not there is a second hole in your sink or counter that’s ready to accept an additional tap. Is there?

    But first things first. What are the tools that you will need for the installation?

    • Screwdriver
    • Adjustable wrench
    • Variable speed drill (only for dedicated faucet)
    • 1/2″ drill bit (only for dedicated faucet)
    • Utility knife
    • Teflon tape

    faucet installation

    Finding the Right Spot

    The great thing about most under sink purifier systems is that they are compact and small, so you can easily place them in a cabinet beneath your kitchen sink.

    What’s important is that there is a cold water line that’s easily accessible. Warm water will damage your filters, so you want to stay away from it! You should also make sure that you have sufficient water pressure to guarantee optimum filtration performance.

    Installation: Step-by-Step Instructions

    Please note that you should always consult the instruction manual provided by the manufacturer.

    (A) To install a direct connect system follow these instructions precisely:

    1. Turn off the cold water supply under your kitchen sink.
    2. Disconnect the main faucet.
    3. Connect the inlet hose of your already assembled system to the water supply valve. Then connect the outlet hose to the faucet. Apply a couple wraps of Teflon tape if needed.
    4. Tighten any fixings with a wrench if necessary. In case there are quick connect fittings, push the tubing in, then gently pull back to make sure the connection is secure.
    5. Secure the system under the sink with screws.
    6. Slowly turn on the cold water supply.
    7. Check for leaks!
    8. Flush the filter(s) as per manufacturer instructions before you start using the water.
    9. Done!

    B) To install an under sink system that uses a dedicated faucet follow these instructions precisely:

    1. Turn off the cold water supply under your kitchen sink.
    2. Disconnect the main faucet.
    3. Install a T-valve onto the cold water pipe. Please note: You might have to use an additional adapter. Apply a couple wraps of Teflon tape if needed.
    4. Drill a hole for the extra faucet if needed. There might already be a spare hole covered by a chrome cover or in case you don’t use your spray hose, you can remove it and mount the faucet there.
    5. Mount the faucet.
    6. Connect the inlet hose of your already assembled system to the cold water supply. Then connect the outlet hose to the new faucet.
    7. Tighten any fixings with a wrench if necessary. In case there are quick connect fittings, push the tubing in, then gently pull back to make sure the connection is secure.
    8. Secure the system under the sink with screws.
    9. Slowly turn on the cold water supply.
    10. Check for leaks!
    11. Flush the filter(s) as per manufacturer instructions before you start using the water.
    12. Done!

    Video

    Still not sure if you can do this? Check out this YouTube video for help. Also, a lot of manufacturers provide their own installation videos on their websites, which make another great resource!

    https://www.youtube.com/watch?v=3ZM7Tjpem4w

    How to Replace an Under Sink Water Filter Cartridge

    Even if you chose to call a professional plumber to do the installation for you, once your under counter system is plumbed in, you should be able to maintain it all by yourself. All you need to do is replace filters from time to time.

    How often? There is no general rule to this as it depends on individual filtration capacities. It could be as much as twice per year or only once every 3 years. This is why it’s important that you always follow the manufacturer’s instructions.

    Filter Replacement: Step-by-Step Instructions

    To replace a filter here is what you need to do:

    1. Turn off the cold water supply under your kitchen sink.
    2. Drain all remaining water from inside the system by opening the faucet.
    3. If your system has filter housings, unscrew them using a filter wrench. Have a bucket at the ready to prevent water from spilling all over the place.
    4. Remove the old filter cartridge.
    5. Clean the housing if need be.
    6. Insert a new cartridge.
    7. Double check that the rubber O-ring is still in place and screw the housing back on. Tighten carefully.
    8. Turn the cold water supply back on.
    9. Check for leaks!
    10. Flush the filter(s) as per manufacturer instructions before you start using the water.
    11. Done!

    If your system features a twist on/off design, you can replace filters without the need for tools and without having to turn off the cold water supply at all. Simply remove the old filter by giving it a quarter turn. Then twist on a new one.

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    If you have any questions about under the sink water filter systems or any other type of water filter really, please don’t hesitate to leave a comment below!

    And don’t forget to come back to this page from time to time, as we are going to add new under sink water filter reviews occasionally.

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