The 10 Best Under Sink Water Filter Reviews

Until recently, water filters were not considered essential for most households. That has changed thanks to several high-profile incidents, including the lead poisoning of many people in Flint, Michigan through the municipal water supply.

Even though your water has been treated and decontaminated by your local government at a water treatment facility, the service pipes that connect the main water line to your home may be a source of contamination. Even if your water has been purged of dangerous heavy metals like lead and arsenic, it may still give off a powerful chemical odor or taste. That’s from all the chlorine that the municipal water treatment facility dumps in the water.

Here's the other thing to consider: legal does not always mean safe. Water that has received a passing grade from the federal government does not mean it would pass the latest health guidelines. The legal limits for dangerous contaminants in tap water have not been updated 20 years. The only way to make sure that your tap water is safe to drink is to filter it yourself.

If you want consistently clean drinking water, you need to filter your water at the point of service. That means with an under sink water filter. This article will go through the 10 best under sink water filters, compare carbon filtration and reverse osmosis technology, and help you determine if you want an under sink water filter or a whole-home system.

Our Top Pick for 2020

CuZn UC-200 Under Sink Water Filter

We consider the CuZn UC-200 the easiest and most cost-effective way to start removing lead, chlorine, sediments, and heavy metals from your drinking water. With a 50,000-gallon capacity, these sturdy filters last roughly five years depending on your water use, which is similar to much more expensive units. What really makes this model stand out is its simple installation. It takes less than five minutes. Unlike other under-sink water filters, the CuZn UC-200 doesn’t require an additional faucet.

Pros
Removes 98% lead, mercury, arsenic, chlorine
5-minute installation is best in class
Filter lasts 5 years or 50,000 gallons

Cons
Bulky
Does not remove total dissolved solids

Factors to Consider in an Under Sink Water Filter


Though there are many things to consider when buying a filtration system, these are the factors we took into account in comparing the best under sink water filters for this article:

- Water Pressure

Water pressure is incredibly important when choosing an under sink water filter. There’s almost nothing more annoying than waiting three or four minutes to fill up a glass of water. Some filters reduce the water pressure so much that people avoid using them when filling up large containers, which defeats the purpose of purchasing on in the first place. Water pressure is especially important if the under sink water filter does not come with a separate faucet.

Generally speaking, the better water pressure a unit has the fewer contaminants it is removing. The reverse is also true. We did the research to find under sink water filter systems with excellent filtration and excellent water pressure, but you should know that this tradeoff exists in every unit.

Also, keep in mind that the more your filter has to work, the lower the water pressure is going to be. If your water is generally clean and you just want to filter out a small amount of sediment and chlorine for smell and taste, you can get away with a filter with subpar water pressure. If you know you are going to be filtering lots of sediment and/or heavy metals, look for a system with excellent water pressure.

- Filtering Capacity

Here’s the first thing to remember: No under sink water filter (or any kind of water filter) is 100% effective at removing all contaminants from water. That's just the nature of water filters in general. That's why you need to know what you want to filter before you start shopping. We wrote these best under sink water filters reviews so you can quickly look through the best systems available, but you still need to know what’s in your water before making a purchase.

Use a home water quality testing kit before you buy a water filter. This will show you what contaminants you need to be concerned about in your water. This 10 minute Drinking Water Test Kit available on Amazon tests for lead, pesticides, chlorine, bacteria, nitrates, nitrates, iron, copper, alkalinity, pH, and hardness like magnesium and calcium.

What a filter can remove from your water depends on the components of the filter cartridge. Filters are always better at removing some contaminants than others. A model may remove all sediment and chemicals but not remove lead and heavy metals. Many models can remove chemicals, sediment, and heavy metals like lead, but not arsenic III.

- Installation

Installation is a hugely important consideration when comparing under sink water filters. If you have some plumbing skills or are not in a rush to get your system set up, you may opt for a system that requires between an hour and several hours of installation. If you don’t have many tools, don’t have experience with plumbing, and need to start filtering your water right away, you should choose a model that says “easy installation” underneath the Pros section. Some of our 10 best under sink water filters can be set up in just five minutes.

Another thing to keep in mind: If a unit is complicated to install, there’s a chance that you will damage it and require a spare part or an entirely new unit. If you need to hire a plumber to help you install the unit, you’ll need to factor that into the total price.

Our top pick for 2020, the CuZn UC-200 Under Sink Water Filter, has a 5-minute installation. Others will take several hours. Luckily, this list only includes models made by companies with excellent customer service representatives that can help you out if you get stuck. Many of the models on this list are designed to be DIY and come with instructional installation videos.

The last thing you want to consider relative to installation is how difficult it will be to change filters. Some models require just five or ten minutes to put in a new filter and only require a change every several years. Others are quite difficult to change and require new filters roughly every six months. No matter what under sink water filter you choose, you are going to be making a compromise between convenience and price.

- Longevity

The other thing you want to consider when shopping for an under sink water filter is its longevity. If you are inexperienced in plumbing and looking for minimal maintenance, you want a model that only requires a new filter every several years. Most cartridges that are rated for three to five years of service are better built than those requiring frequent changes and are less likely to break.

Take note that any estimate about how long a cartridge last that’s communicated as a timeframe — six months, two years, five years, etc. — is just an estimate. The size of your family and the amount of water you use every year will impact how long your cartridge will last. Also, the more contaminated your water is, the shorter your cartridge’s lifespan will be.

Lastly, most real-world water is dirtier than the water manufacturers use to test their devices. Be prepared to replace your filter’s cartridges more frequently than the manufacturer says you will.

Best Under Sink Water Filter Reviews

Home Master TMAFC-ERP Under Sink Water Filter - Reverse Osmosis

The Home Master TMAFC-ERP under sink water filter is one of the best of its kind on the market. It comes with ultra long-lasting filters and is eco-friendly with a low wastewater to filtered water ratio of 1:1. The only downside is the price, but its features more than compensate for its elevated price tag.

The TMAFC-ERP is made in the USA by an NSF listed manufacturer, Perfect Water Technologies, Inc., with NSF certified components. It comes with a reverse osmosis (RO) membrane, pre-filters to protect the RO membrane, and a remineralizer that adds healthy minerals back into the water for improved taste.

- Excellent Flow Rate and Little Waste

Most RO water filters are wasteful, but not the TMAFC-ERP, which includes a permeate pump that improves system efficiency with an 80% reduction in wastewater. Many other models function on a 3:1 or even 5:1 ratio of wasted water to purified water. With a ratio of 1:1, the Home Master TMAFC-ERP is likely the least wasteful RO filter. Amazingly the permeate pump uses energy from the rejected water, so the system does not require electricity.

- Comprehensive Water Filtration

In addition to an RO membrane, the TMAFC-ERP has 3 filters: a sediment filter made of spun poly, a catalytic carbon filter, and a coconut shell activated carbon filter. Together, these systems filter out up to 99% of heavy metals, dissolved solids, and chemicals. The catalytic carbon is highly effective at removing chloramine, a chemical used by many municipal water treatment centers instead of chlorine.

Once the water has been filtered clean, the remineralization system injects healthy minerals like magnesium and calcium back into the water, making it more alkaline and tasty.

- Innovative Filter Design

In most RO water filters, the filter housing is reused over and over again, even after the filter is changed. This reuse increases the chance of contamination. That’s why the Home Master TMAFC-ERP is made with a modular filter design. Both the filter and its housings are incorporated into a single unit that is installed and disposed of together. The manufacturer recommends changing the filter every 2,000 gallons, or roughly once a year depending on how much water you use.

- Installation

RO systems are notoriously difficult to install. The TMAFC-ERP is not too difficult but may require professional help for inexperienced users. As we mentioned before, the membrane and filters and housings come assembled, so you don’t have to get into the nitty-gritty with the components. That being said, you may need the help of a plumber to get the system hooked up to your water line if you don’t have experience. Installation takes roughly an hour.

Pros

  • Best available wastewater to filtered water ratio (1:1)
  • Removes 98% lead, mercury, arsenic, chlorine
  • Mineralization for alkaline water
  • Improves taste and odor significantly
  • NSF listed

Cons

  • Expensive
  • Difficult installation

    2. APEC Alkaline Mineral pH+ 6-Stage Under Sink Water Filter - Reverse Osmosis

    ​The APEC Alkaline Mineral pH+ 6-Stage Under Sink Water Filter removes lead, chemicals and other toxins with the best of them. It also reintroduces beneficial minerals like calcium and magnesium that are removed during filtration to leave you with clean, alkalized, great-tasting water.

    - Five Stage System

    The APEC pH+ 6-Stage Water Filter purifies water in five stages. The first stage includes a rough polypropylene filter that removes large particles like rust and sediment. Next, the water passes through two carbon membranes that remove 99% of chlorine.

    To eliminate dangerous heavy metals like lead and arsenic and remove bacteria and viruses, the water then moves through a High Rejection TFC RO membrane. Finally, before leaving the system’s water storage tank, the water passes through a coconut shell activated carbon filter to ensure it tastes and smells fresh.

    This five-step system can deliver 90 gallons of purified water every day.

    - Alkalization

    Now that the water has been stripped of heavy metals, viruses, sediment, and other contaminants, it’s time for the alkalization stage, in which calcium carbonate is added to the water to improve taste and smell.

    The pH level of the purified water produced by this model will increase by between 1 and 2 points. So if you tap water naturally has a pH of 5, you’re likely to see a final pH of 6.5 or 7.

    - Installation

    Like the other high-end RO systems, the installation of the APEC pH+ 6-Stage Water Filter takes about an hour. The APEC pH+ 6-Stage Water Filter comes with all of the materials you need, but you will need a drill and a screw for some basic drilling and screwing work. Total installation time may be more than an hour if you lack basic plumbing experience.

    Pros

    • Removes 98% lead, mercury, arsenic, chlorine
    • Mineralization for alkaline water
    • Improves taste and odor significantly
    • Responsive customer service

    Cons

    • Requires separate faucet
    • High wastewater to filtered water ratio (3:1)

      3. iSpring RCC7AK 6-Stage Under Sink Water Filter - Value Reverse Osmosis

      ​This celebrated 6-stage under sink water filter from iSpring relies on multi-stage filtration and remineralization/alkalinization for improved taste and odor. It is certified to NSF standards, removing 98% of lead and 99% of thousands of other contaminants, including chlorine, arsenic, bacteria, and viruses.

      When it comes to getting the most bang for your buck, you can’t do much better than the RCC7AK. It won the WQA Gold Seal from the Water Quality Association, a not-for-profit association representing residential, commercial, and industrial water treatment industry across the globe.

       Five Stages of Filtration

      The RCC7AK filtration process begins with three pre-filters: a fine mesh filter to trap sediment, a granular activated carbon core, and a carbon block. Next comes the RO membrane, which has pores 0.0001 microns in diameter, and another carbon filter. The last stage is alkalization to reintroduce healthy minerals that were removed during filtration.

      - Alkalization

      Water that’s filtered by the RCC7AK’s five-step filtration system is so clean that it lacks beneficial minerals that are good for your health and improve the taste and odor of the water. That’s why the RCC7AK has a sixth stage, remineralization, where calcium and magnesium are added to the water, giving it the neutral yet slightly sweet taste of spring water.

      - Longevity

      The RO membrane in the RCC7AK can last up to three years thanks to the three protective pre-filters. Other less expensive components in the system last just one year, which is common in reverse osmosis filters. Thanks to a clear housing in the polypropylene pre-filter, you can watch as sediment builds up and get a good idea of when it should be changed.

      If your home has naturally low water pressure, you may want to purchase a permeate pump to speed things up. A permeate pump will increase water flow while also reducing the amount of water wasted. For every three gallons of purified water the RCC7AK produces, it wastes three gallons of water.

      - Installation

      For a RO under sink water filter, installation is relatively easy. Unlike the previous systems on this list, plumbing skills are not required. You should be able to complete the installation without problems in under an hour.

      All necessary parts for installation are included in the package. Simply push the tubing provided ½ inch deep into the system’s quick-fitting connectors and lock them. Installation does not require any threading pipes.

      The instructions are well-organized and backed by instructional videos by iSpring. If you’re installing the filter and run into problems, iSpring technical support is available and responsive. Another added bonus of the RCC7AK is its compact size. It fits neatly under a standard kitchen sink.

      Pros

      • Affordable
      • Removes 98% lead, mercury, arsenic, chlorine
      • WQA award winner
      • Excellent customer service

      Cons

      • High wastewater to filtered water ratio (3:1)

        4. APEC WFS-1000 3-Stage Under Sink Water Filter - Carbon Filtration

        ​One of the most popular under sink water filters is the APEC WFS-1000. It uses a three-stage filtration system that removes most contaminants and chemicals, but not heavy metals like lead.

        The filter is designed, engineered and assembled in the USA with quality, long-lasting components. So perhaps it’s no surprise that the filter comes with a 1-year satisfaction guarantee and lifetime support by a WQA certified water specialist.

        As a carbon-based filter, the APEC WFS-1000 does not have any RO functionality. It is guaranteed to remove chlorine taste and odor as well as sediment. It can take feed water pressure of anywhere between 20 and 85 psi. Despite the fact that water must pass through three separate filters, the APEC WFS-1000 has excellent water pressure.

        - Installation

        All required parts needed for the installation come in the box. The filter has pre-drilled holes for easy wall mounting because the system needs to be placed upright underneath your sink.

        Installation occurs in two parts. First, you assemble the filters and housings onto the main system. This basically means putting the sediment filter into the first stage housing, the carbon filter into the second stage housing, and the second carbon filter into the third stage housing. Then you use the wrench provided in the box to tighten the housings.

        Next, you connect the system to the cold water supply under the sink, drill a hole for the included faucet (or use an existing hole), mount the faucet, and connect the system. The filter does not need to be mounted underneath the sink. It can rest against an interior wall or stand upright but needs to remain standing up during use.

        Pros

        • Affordable
        • Good water pressure
        • Responsive customer servic

        Cons

        • Does not remove fluoride, lead, other heavy metals, or total dissolved solids
        • Difficult installation
        • Requires additional faucet
        • Faucet only comes in one finish, stainless steel

          5. APEC ROES-50 5-Stage Under Sink Water Filter - Value Reverse Osmosis

          ​The APEC ROES-50 reverse osmosis water filter made our list thanks to its high-quality filtration and affordable price.

          - Excellent Quality

          The APEC ROES-50 is the definition of quality. It was designed, engineered, and assembled in the USA and is backed by a 2-year extended manufacturer warranty if you register your product online. It removes 99% of contaminants, including dangerous heavy metals like lead and arsenic, chemicals like chlorine, and dangerous bacteria and viruses.

          - Great Capacity and Longevity

          The APEC ROES-50 is rated at a capacity of 50 gallons per day if your water pressure is 60 psi or 30 gallons a day if your water pressure is 50 psi. It can filter a maximum load of 2000 ppm total dissolved solids. Its filters are long-lasting even when filtering highly contaminated well water. It comes with a lead-free designer faucet and food-grade tubing and parts.

          - Installation

          The APEC ROES-50 comes with all required parts as well as clear written instructions and instructional videos. Designed to be DIY. No plumbing experience is required to install the APEC ROES-50. The filter’s quick-connect fitting doesn’t require extra lock clips to seal leaks. The system does not rely on a leak detector like other brands.

          Pros

          • Removes lead and other heavy metals
          • Responsive customer service
          • 2-year warranty

          Cons

          • High wastewater to filtered water ratio (3:1 according to company, users report 8:1 or higher)

            6. CuZn UC-200 Under Sink Water Filter - Carbon Filtration

            ​There’s no easier or more cost-effective way to start removing lead, chlorine, sediments, and heavy metals from your home’s drinking water than the CuZn UC-200. Each filter has a super long, 50,000-gallon capacity that will last most families 5 years.

            Unlike many other under sink water filters on this list, the CuZn UC-200 can be installed in just a few minutes with zero plumbing experience or special tools. It also doesn’t require an additional faucet. Just connect it up to your cold water line and you’re ready to go.

            - Three Layers of Filtration

            The CuZn UC-200’s outermost filter consists of micro-sediment trapping membranes that catch things like rust, sand, and plastic fibers. Inside this layer is an acid washed coconut shell activated carbon filter that removes chemicals like chlorine, chloramine, pesticides, and herbicides. Finally, there is an NSF-certified medium called KDF 55 that controls scale, algae, and bacteria while removing heavy metals like lead and mercury.

            The CuZn UC-200 does not require alkalization because its three layers of filtration allow healthy, natural minerals like calcium and magnesium to pass through. In other words, you get the best of both worlds: clean, contaminant-free water that tastes great.

            - Excellent Filter Life

            Depending on the quality of your municipal water, the CuZn UC-200 should last for around 50,000 gallons or five years. The exact longevity of your system will vary depending on the quality of your water, which in turn can be impacted by any number of things. Unless you live in an area with extremely contaminated water or you live near a long-term active construction project that churns up lots of sediment in the water, the CuZn UC-200 is a true set-it-and-forget-it water filter. Set a reminder for five years from your date of installation and you’re done!

            - Easy Inspection

            For peace of mind and in order to ensure your filter is cleaning your water as it should, the CuZn UC-200 includes a clear housing that allows you to see if the micro-sediment trapping membranes are overloaded. If this happens before your five years are up, contact the manufacturer’s customer service line to see if you can get a replacement. By all accounts, the support team has gone above and beyond to ensure customers are satisfied with their product.

            - Installation

            There’s no under sink water filter that has a simpler installation process. All you need is an adjustable wrench and five minutes of free time to get the filter up and running. All of the required components come with the filter. The manufacturer has provided written instructions as well as video tutorials you can use if you run into trouble. If you have non-standard plumbing and are struggling with installation, reach out to the CuZn live support staff who will walk you through your installation.

            Simply connect the braided stainless steel compression hose that comes with the filter to the cold water line. Amazingly, you can even connect the filter to the hot water line. CuZn says the filter’s durable filter housing can take hot water and the filter can clean it, though not to the same level it can with cold water.

            Pros

            • Removes 98% lead, mercury, arsenic, chlorine
            • 5-minute installation is best in class
            • Filter lasts 5 years or 50,000 gallons

            Cons

            • Does not remove total dissolved solids

              7. iSpring US31 3-Stage Under Sink Water Filter - Carbon Filtration

              ​This compact 3-stage under sink filter includes a large, 10-inch sediment filter and two carbon filters that will take out any contaminants larger than 5 microns.

              All iSpring US31 units can filter common sediments like rust, dust, dirt, and sand and remove bacteria, parasites, and chlorine that causes bad taste and odor. Be sure to check which kind of filter your unit comes with. If it comes with the unique GAC filtration in the second layer, it will also be able to remove lead, arsenic, and other heavy metals.

              - Installation

              Installation is relatively easy for the iSpring US31, but it won’t be a 5-minute installation. The unit includes all required components to set up the filter and the faucet. All you will need are a few tools. The installation kit includes an ample supply of quality water line, all required fittings, and a roll of Teflon tape.

              The iSpring US31 comes with a faucet that is 11.25 inches tall, so keep that in mind when planning your installation. The filters have to sit upright when in use. The system cannot be used if the filters are sitting in a horizontal position. For this reason, you may need to mount the filter to the wall underneath your sink.

              Pros

              • Removes chlorine taste and odor
              • Removes sediments, sand, soil, silt, rust
              • Simple installation
              • Eco-friendly
              • Existing faucet can be used with the system

              Cons

              • Faucet requires lots of space
              • Filter must stay upright, may require mounting

                8. Woder WD-S-8K-DC Under Sink Water Filter - Budget Option

                ​The Woder WD-S-8K-DC is a budget option that still delivers powerful filtration capabilities. It doesn’t remove lead and other heavy metals, but it does remove chlorine and the bad taste and odor that come with it. It also removes sediments like sand, soil, silt, and rust.

                Don’t let the small price fool you. The filter is NSF approved. Its components and filter materials are all NSF approved as well. The Woder WD-S-8K-DC filters are good for 10,000 gallons of water, so you will be able to use it without changing the filter for roughly 3 years depending on how much water you use and how contaminated your water is.

                For added convenience, this filter doesn’t require an extra faucet so you can enjoy clean-tasting water from your ordinary kitchen faucet.

                One downside of the Woder WD-S-8K-DC is that it tends to lower water pressure considerably. Expect a reduction of up to 20%, which may or may not be a problem depending on how strong your water pressure is to begin with.

                - Installation

                Installation takes just a few minutes. All components needed to install the Woder WD-S-8K-DC come in the box. The filter’s ‘Direct Connect’ hoses fit the standard 3/8” water valves that you find in almost every kitchen and bathroom sink in the United States.

                Simply install the 3/8” ‘Direct Connect’ hose to your cold water line and faucet step underneath your sink. The only tool that’s needed is an adjustable wrench to tighten the connectors.

                Pros

                • Removes chlorine taste and odor
                • Removes sediments, sand, soil, silt, and rust
                • Filter change every 3 years
                • Easy filter change takes 5 minutes

                Cons

                • Does not remove lead
                • Slows water pressure by up to 20%

                  9. Filtrete Under Sink Quick Change Water Filter - Budget Option

                  ​The cheapest model on our list also happens to be made by one of the most celebrated manufacturing companies in the world, 3M. The Filtrete Under Sink Water Filter won’t remove lead and other heavy metals, but it will remove chlorine taste and odor, microbial cysts, and sediments like sand, soil, silt, and rust.


                  Test your water with a home water testing kit to see if you have lead contamination. If you don’t this could be an excellent, cost-effective choice for cleaner, better-tasting water.

                  The Filtrete filter doesn’t require a separate faucet for the filtered water. It connects straight to your cold water line. All water that passes through your faucet will be filtered. The capacity on this filter is 10,000 gallons of water. You can expect to need to change the filter in roughly three years. That timeframe could be considerably shorter depending on the quality of your water (how much the filter has to remove from the water) and how much water you use.

                  - Installation

                  This is a true DIY installation. It takes less than 30 minutes. All you have to do is turn off the water where you are installing the filter and attach the faucet water supply hose to the quick connect output on the Filtrete filter head. Next, attach the water supply hose to the quick connect input on the Filtrete filter head. Attach the filter with a quick ¼ turn, and turn on the water.

                  Pros

                  • Removes chlorine taste and odor
                  • Removes sediments, sand, soil, silt, rust, and microbial cysts
                  • Maintains water pressure

                  Cons

                  • ​Does not remove lead

                    10. Home Master TMHP Under Sink Water Filter - Reverse Osmosis for Well Water

                    ​We saved one of the most advanced under sink water filters on our list for last. That’s because this is a specialized reverse osmosis and water softening system that is ideal for well water. If you have well water that needs to be softened and filtered, look no further.

                    Well water is a completely different beast than tap water. Well water isn’t treated with chemicals like chlorine, fluoride or chloramine, so you don’t need a filter that specializes in treating these common tap water contaminants.

                    What well water does have a lot of is sediments like rust and sand, dangerous microorganisms, and heavy metals like lead. It also has “hard water” like magnesium, calcium, and iron that can damage appliances, reduce the effectiveness of laundry and dish soap, and damaged skin and hair.

                    The Home Master TMHP takes care of all these contaminants at once, filtering and softening while maintaining a super, eco-friendly 1:1 waste to filtered water ratio.

                    - Advanced Purification and Softening

                    First, to prevent iron from damaging the TMHP’s RO membrane, water pass through an iron pre-filter that contains an advanced redox media called KDF85. The pre-filter and RO membrane remove 99% of chemicals, sediment, pesticides, and heavy metals including water-soluble lead, mercury, chromium, etc. The pre-filter also removed 98% of the iron in the water, eliminating the metallic taste common to well water and protecting dishes and the sink from rusting.

                    - UV Light Eliminates Viruses and Bacteria

                    Next, the water passes through a UV light to kill disease-causing microorganisms. UV light breaks molecular bonds in viruses and bacteria which prevents them from causing infections and illness. UV light is one of the four methods approved by the FDA to clean water.

                    - Alkalinization

                    Lastly, because multiple rounds of filtration can leave water lacking in mineral content, the TMHP reintroduces a small amount of beneficial minerals (calcium and magnesium) into the water. This process will both protect the water tank from degrading and improve the taste of the water.

                    - Installation

                    Installation for this system is difficult and can be time-consuming if you are inexperienced. It comes with all the required materials for installation. Because the system incorporates a UV light, it requires electricity, which makes the installation even more difficult.

                    Pros

                    • Removes 99% lead, mercury, arsenic, chlorine
                    • Removed 98% iron
                    • Best available wastewater to filtered water ratio (1:1)
                    • Mineralization for alkaline water
                    • Improves taste and odor significantly

                    Cons

                    • Expensive
                    • Difficult installation
                    • Requires electricity

                      Carbon Filtration Versus Reverse Osmosis

                      Now that we’ve introduced the best under sink water filters, let’s take a closer look at the differences between carbon filtration and reverse osmosis.

                      Carbon filters are sometimes called “carbon block” or “activated carbon.” Both kinds of filters clean water using a specially designed carbon medium. As the water passes through the porous carbon, impurities bond with the carbon. Carbon is the medium used in numerous filtration products, from pitchers to faucet-mounted filters to whole-home filters. Carbon filtration is especially good at removing chlorine taste and odor from treated tap water. It can also capture large particles like sand and rust.

                      Reverse osmosis works by separating water molecules from other molecules. It does this by forcing the water through a semipermeable membrane. Reverse osmosis systems often include several different stages, a pre-filter stage to protect the RO membrane, the RO membrane, and a storage tank to hold the filtered water. Each step in the reverse osmosis system plays a part in ensuring the water is clean.

                      The pores in an RO membrane are so small that they can remove a much wider range of contaminants than carbon filters can. Carbon filters can be designed to remove specific contaminants, like lead or arsenic, but RO systems do this by default.

                      As a rule, carbon filters much less from your water than reverse osmosis does. How much less it removes depends on the rating of the system, which ranges from 0.5 micron to 50 microns. Many carbon filtration systems have NSF Class I particulate rating, which means that 85% of 85% of .5–1μm sized particles are removed. For reference, a reverse osmosis filter will filter down to about .001μm, a difference of 500x.

                      If you’re going with a carbon filtration system, make sure it at least has an NSF rating. Search the NSF database here to learn exactly what contaminants each of the models above will protect you from.



                      Under Sink Versus Whole-Home Water Filters


                      The last thing you need to consider when looking at an under sink water filter is whether you are going to end up filtering all the water in your home with a whole-home water filter, which filters water at the point it enters your home from the municipal line. If you think you may invest in a whole-home water filter, there’s no need to buy an under sink filter.

                      - Under Sink

                      Under sink water filters are installed at one access point in the home. Only the water coming from one faucet will be filtered. The advantage of an under sink water filter is that it cant filter large quantities of water without taking up too much space. The downside of these filters is that they can be expensive, especially if you want to filter the water from multiple faucets, and they may require modifications to your plumbing.

                      - Whole-home

                      Whole-home water filters remove contaminants from all the water that enters your home. That includes the water that is used for your water boiler, your appliances, your shower, and your toilets. Whole-home water filters are installed near the homeowner’s property line where the municipal feed connects with the home’s service lines.

                      The major advantage of a whole-home water filter is that it will likely soften water as well as filter it. If you are dealing with hard water and need to filter your water, then a whole-home filtration and softening system can make your water safe for drinking and remove the hard minerals that damage appliances, reduce the effectiveness of dish and laundry soap, and cause limescale buildup. The only downside of these systems is their high cost. Installation requires a professional and maintenance can be costly.

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