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Best Under Sink Water Filters of 2021

Concerned about the purity of the water in your kitchen faucets? We’ve reviewed the best under sink water filters so you can be sure your water is safe.

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Best Under Sink Water Filter Reviews of 2021

Home Master TMHP-L

Home Master TMHP-L Undersink Reverse Osmosis Water Filter

The most complete water filter

Top-notch 9-stage water filtration and purification system removes up to 99% of water contaminants.

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1 Home Master TMHP-L Review

Boasting a BPA-free construction and removing up to 99% of water contaminants, the Home Master TMHP-L is an under sink water filter designed to provide the purest possible water.

The filter comes with a luxury brushed nickel faucet and a fridge connection kit, ensuring all your water is filtered and purified before consumption.

A great feature is the patented Full Contact technology which adds magnesium and calcium during the purification process, enhancing the taste of the water.

The included permeate pump reduces water waste while increasing water production and the innovative technologies involved also eliminate the most common problems of the traditional reverse osmosis filters, including slow flow rate, leaks, and water waste.

Creating pure water with its 9-stage system and suitable to connect to your fridge, the Home Master TMHP-L is the best under sink water filter on the market.

Best value
iSpring RCC7AK

iSpring RCC7AK 6-Stage Under Sink Water Filter

Perfect for most homes

High capacity water filtration able to remove almost all contaminants, lead included.

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2 iSpring RCC7AK Review

The iSpring RCC7AK is a great under sink water filtration system for the homeowner searching the best value for money.

This system comes with an advanced reverse osmosis membrane developed to remove pollutants but preserve the natural taste of water by maintaining the helpful minerals.

The under sink water filter is easy to install without professional help thanks to the comprehensive instructions and videos available, while the iSpring technicians offer further guidance via phone if needed.

Similar to our best-in-class pick, this reverse osmosis system provides tap water via a stylish European-style faucet.

Maintenance is made easy by the see-through filter housing which ensures a quick inspection whenever needed. Reliable, easy to install, and easy to maintain, the iSpring RCC7AK brings all you could wish from a best-value pick.

Also great

APEC ROES-PH75 6-Stage Drinking Water Filter

A great alternative

High-quality filters provide pure and pH-enhanced drinking water.

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3 APEC ROES-PH75 Review

Similar to our best-value pick, the APEC ROES-PH75 also provides a 6-stage filtration and purification, delivering healthy tap water in the blink of an eye.
Engineered with quality in mind, the unit comes with a lead-free faucet and FDA Food-Grade Certified tubing.

Like the iSpring, this under sink water filter comes with a water alkalization system which uses a US made calcium cartridge to ensure pH enhancement and a great taste of the water.

Moreover, this water filter is also easy to install by yourself and comes with detailed instructions and guidance videos.

Removing most water contaminants, easy to install and coming with a lead-free faucet, the APEC ROES-PH75 is a great alternative if you want to make sure the system is engineered and assembled in the USA.

Best budget

APEC WFS-1000 3-Stage Under-Sink Water Filter System

Less sophisticated, but cheap

A no-frills three-stage water filter ideal for purifying tap and well water in a breeze.

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4 APEC WFS-1000 Review

The APEC WFS-1000 is a three-stage water filtration system designed to remove most pollutants from either tap or well water.

The three high-capacity filters provide a dependable filtration for a longer time than standard filters, needing to be replaced only once a year.

At the same time, the compact design is easy to install under the sink and comes with a stylish lead-free faucet.

A slight drawback of this system is the lack of the re-mineralization; the water provided is still pure and safe to drink, but it could be less tasty than mineral water. Nevertheless, the attractive price point and great quality counterbalance this minor flaw.

FDA certified, easy to install, and ready to use in less than two hours, the APEC WFS-1000 is a great pick for the budget-savvy homeowners.

1. Countertop vs. pitcher vs. under sink water filters

Homeowners concerned by the purity of the water coming out the faucet can install a water filter to improve its quality.

There are several filter styles, but the most commonly used are the countertop and pitcher, two types of filters that can only remove impurities, and under sink water filters, more complex systems designed to remove impurities and improve the quality of the water.

  • Countertop water filters: Can either connect to your faucet or come as freestanding units that use gravity to purify water. Both have advantages and disadvantages, but the gravity-fed countertop filters are the most beneficial in case of power outage, as they do not require an alternative source of energy, such as a power generator, to run.
  • Pitcher filters: Are similar to the gravity-fed countertop water filters in that they use gravity to clean water. These filters typically do a great job in removing chlorine from water but rarely remove other contaminants.
  • Under sink water filters: Are a convenient solution for those with a restricted countertop space. These filters are the most complex to install but also the most effective in removing contaminants. Depending on the type of filters involved, the under sink water systems may need to be connected to a source of electricity.

2. Why invest in an under sink water filter?

Both the countertop and pitcher filters do a great job in softening hard water, but they rarely remove contaminants such as bacteria, viruses, and heavy metals. The best under sink water filters, on the other hand, can typically:

  • Remove heavy metals and arsenic from water
  • Rebalance the alkalinity of the water by adding essential minerals
  • Reduce limescale deposits
  • Reduce the nitrite and nitrate concentration in water
  • Remove chlorine and fluoride from water
  • Reduce bad odors and improve the taste of the water

3. Types of under sink water filters

You can choose between conventional and simple under sink water filters.

  • Conventional filters: Require you to divert the cold water circuit through the system via a connection consisting of a short tube. The filtration system removes water contaminants and delivers pure water through a separate faucet that needs to be installed on your sink. Unfiltered hot and cold water will still run through the sink’s faucet, and you will sometimes have to alter the conformation of your countertop or sink to mount the new faucet.
  • Simple filters: Are less popular than the conventional systems but they have the advantage of connecting to your main faucet. All cold water will run through the filter and will come out from your sink’s faucet, while the hot water will remain unfiltered. This system requires you to bring no alteration to your countertop or sink design, and like the conventional systems, it uses filter cartridges to purify water. However, due to the higher volume of filtered water, you’ll have to change these cartridges more frequently.

What type of under sink water filter is best?

Both types of filters come with pros and cons. Simple filters deliver a higher water pressure due to the simplicity of their design which allows water to flow faster. Conventional systems have a reduced water flow but are more effective in cleaning water.

If you want to drink the purest possible water but don’t want to wait for ages for your glass to fill up, a conventional under sink water filter capable of outputting a water pressure between 45 and 70 pounds per square inch (PSI) is perhaps your best choice.

4. Water filtration methods

Under sink water filters can use different technologies to remove impurities and contaminants from water. There are various types of filter systems employed, and the more advanced ones typically combine different technologies and multiple steps for a better filtration.

  • Activated carbon filter: Consists of a porous material designed to trap chemicals, bacteria, and viruses; they are ideal to clean water from pesticides and other chemicals, including chlorine. Moreover, the carbon filter also improves the taste of water and removes any bad odors.
  • Sediment filter: Is perhaps the simplest and is designed to only trap macroscopic particles such as sand or mud. This type of filter doesn’t remove chemicals, bacteria, and viruses, which means water could still be contaminated.
  • Ion exchange filter: Contains plastic micro-beads designed to bind specific ions and let others pass. These filters do a great job in removing heavy metals but typically don’t remove any pathogens.
  • Ultrafiltration: Is a system commonly employed in rural areas. The filter traps both macroscopic and microscopic particles and needs no electricity to run.
  • Oxidation-reduction filter: Uses a combination of copper and zinc to create a chemical reaction with the various contaminants in water, neutralizing them. This type of filter is often employed for removing chlorine and some heavy metals.
  • Ultraviolet filter: Uses ultraviolet light to kill germs and bacteria but has no further benefit. This type of filter doesn’t remove other contaminants such as chemicals or sand.
  • Reverse osmosis filter: Consists of a semi-permeable membrane designed to trap chemicals, germs, and macroscopic particles. Reverse osmosis systems employ a 5-step filtration, and some of the best under sink water filter systems also have additional filers to remove as many contaminants as possible.

Which technology to choose?

The easiest way to decide which is the best under sink water filter for you is by testing your tap or well water. Reverse osmosis systems do an excellent job in removing most contaminants, but they are expensive and typically don’t remove minerals. In this case, an oxidation-reduction or carbon filter could be more advantageous.

If germs are not a concern but sand or mud is, an ultrafiltration system could be a cheaper alternative to a complex reverse osmosis filter.

In case you want to remove most contaminants, including macroscopic and microscopic particles, chemicals, and heavy metals, the wisest idea is to invest in a six- or nine-stage system designed to filter, purify, sterilize, and enhance the properties of the water. 

5. Filter cartridges

Regardless of the technologies involved, all under sink water filters come with removable cartridges that have to be replaced regularly. This is part of the regular maintenance, and replacing your filters on time ensures the quality of the water is maintained.

How often should you change the cartridge?

There is no precise rule to how often you should replace the cartridges, but it is recommended to follow the manufacturer’s indications, assuming you use the filtration system regularly and as instructed.

In broad terms, low-end filters have to be replaced every six months. More performing filters may only require you to change them once a year while some high-end cartridges withstand up to five years of use before replacement.

6. What other features to look for?

The best under sink water filters must also have the following features:

  • Easy change filters: Traditional systems may require the use of tools and brute force to remove and change the cartridges. To avoid frustration, you must be able to change the cartridges in under ten minutes.
  • Water mineralization: Most under sink water filters remove all contaminants from water, including important minerals like calcium and magnesium. Some systems re-mineralize the water, enhancing its taste.
  • Simple installation: The best under sink water filter must be easy to install without the help of a plumber. Make sure the instructions are comprehensive and easy to follow.
  • BPA-free components: Under sink water filters use plastic tubes to connect to your main water supply, and low-quality tubes may contain bisphenol A (BPA), an industrial chemical associated with adverse health effects in fetuses, infants, and young children. To avoid all risks, invest in a system with BPA-free components.
  • Fridge connection kit: If you have a fridge with cool water or ice dispenser, a fridge connection kit allows you to supply your appliance with filtered water.

7. The Best Under Sink Water Filter for the Money

Best value
iSpring RCC7AK

iSpring RCC7AK 6-Stage Under Sink Water Filter

Perfect for most homes

High capacity water filtration able to remove almost all contaminants, lead included.

Check price on Amazon

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