6 Best Under Sink Alkaline Water Filters (*Update 2023)
Written by: Gene Fitzgerald // Last Updated: Sep 6, 2023
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Top Pick
The best under sink alkaline water filter in 2023 is the USWS All American 6-Stage, because it features powerful water filtration including reverse osmosis, it achieves an alkaline water pH of between 8.5 and 10.0, and it is easy to install and maintain, made in USA, and backed by a 5-year warranty.
There’s a plethora of under sink alkaline water filters out there. Some will make your taste buds tingle with joy, others not so much. That’s why finding the perfect system to transform your water into a refreshing elixir can feel like searching for the Holy Grail.
But fret not! We’ve reviewed over 16 of the top under sink alkaline water filters on the market comparing them to one another. So get ready to revolutionize your hydration game and bid farewell to ordinary tap water!
Contents
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No Time to Read? Check Our List of the Best Under Sink Alkaline Water Filter Systems!
| Filters | Details | |
|---|---|---|
 Best Under Sink Alkaline Water Filter: USWS |
Overall Rating: 5.0/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
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Price: $$$ Type: Reverse Osmosis System Water pH: 8.5-10.0 Minerals: Calcium, Magnesium, Potassium Warranty: 5 Years Read Review: Click |
 Best Non-RO: Crystal Quest |
Overall Rating: 5.0/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
Get 5% Off! Use Code: |
Price: $$ Type: 3-Stage Filter Water pH: Unspecified Minerals: Calcium + Magnesium Carbonates Warranty: 1 Year Read Review: Click |
 Best for Tankless Alkaline RO Purification: Frizzlife PD600 |
Overall Rating: 4.5/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
Get $80 Off! Use Code: |
Price: $$$ Type: Tankless Reverse Osmosis Water pH: >7.5 Minerals: Unspecified Warranty: ? Read Review: Click |
Best Under Sink Alkaline Water Filter Reviews
The under sink alkaline water filters below were rated based on these factors: Treatment process (25%), pH increase (20%), costs (20%), hands-on testing and user opinion (15%), filter capacity (10%), product warranty/support (10%).
Review Order
- US Water Systems All American 6-Stage Alkaline Reverse Osmosis System – Best Overall
- Crystal Quest Alkaline Under Sink Water Filter System – Best Non-RO
- Frizzlife PD600-TAM3 Tankless Alkaline RO System – Best for Tankless Reverse Osmosis Purification
- NU Aqua Platinum Series 6 Stage Alkaline System
- Express Water ROALK5D Under Sink Alkaline Water Filtration System – Best Budget Option
- iSpring RCC7AK Under Sink Alkaline RO Water Filter – Best for NSF-Certified TDS Removal
1. Best Overall: US Water Systems All American 6-Stage Alkaline Reverse Osmosis System
In our opinion, the best under sink alkaline water filter in 2023 is the USWS All American 6-Stage Alkaline Reverse Osmosis System.
The system has a very high quality build and offers excellent filtration for great-tasting, clean drinking water. On top of that, Livation Hydration Technology enriches the water with healthy minerals and increases pH to an alkaline level of around 8.5 to 10.0.
5 out of 5 stars!
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USWS All American 6-Stage Alkaline Water System |
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| Price: | $$$ |
| Filter Type: | RO, 6 Stages |
| Water pH: | ~8.5-10.0 |
| Minerals: | Calcium, Potassium, Magnesium |
| Annual Cost: | ~$150-225 |
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Overall Rating: 5.0/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
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Gallery
Other Specs
- Model: 200-AARO-LIV
- Last Price: $634.95-644.95
- Filter Process: 5-Micron Sediment Pre, 2x Carbon Blocks, RO, Remineralization, Carbon Post
- Membrane Rating: 50 or 100 gpd
- Filtering Capacity: 6 Months to 5 Years
- WxH (System): 16″x24″
- Tank: 11″x16″x11″, 3.2 gal
- Operating Pressure: Up to 75 psi
- Warranty: 5 Years
Key Features & Pros
- This under sink alkaline RO system is 100% Made in America providing highest overall quality.
- 6-stage filtration process purifies and enhances your water:
- In stage 1, a 5-micron sediment pre-filter removes sand, rust, and other dirt. This is primarily to prevent the following filter stages from clogging.
- Next, a carbon block pre-filter removes chlorine and other tastes and odors. It also filters chemicals.
- At filter stage 3, a special-blend 1-micron carbon block targets chloramine (greater than 95%), lead, and cysts.
- Now the reverse osmosis membrane removes any remaining water impurities and contaminants, including arsenic (95%), mercury (98%), nitrate (89%), bacteria (95%), and fluoride (98%).
- In the Livation Hydration chamber, different types of ceramic balls emit calcium, potassium, and magnesium, and also increase water pH while lowering oxidation-reduction potential. This is supposed to help water absorption in your body and also boost your immune system.
- Lastly, a carbon post-filter removes any residual tastes for the most refreshing drinking water.
- You can choose between 2 membranes, depending on how much water you need on a daily basis and how fast.
- A non-electric permeate pump is optional and can be used to boost water pressure.
- Doubles filtration speed for no/shorter waiting times.
- Further improves filtered water quality slightly.
- Reduces clean-to-waste-water ratio by as much as 80%. Less wastewater going down the drain.
- You get higher pressure at the RO dispenser.
- Filter elements use double O-ring for perfect seal.
- Prevents dirty water from bypassing the filters contaminating clean water.
- A large 4.5-gallon tank is included storing clean water for future use.
- You can choose from 4 faucet designs: Chrome, brushed chrome, brushed nickel, stainless steel.
- A free TDS meter for measuring water quality is part of the package.
- A syringe + sanitizing solution is also included. They allow you to sanitize the water filter system during installation and when changing filters.
- Materials are FDA + NSF compliant and 100% BPA-free.
- Installation is really easy according to customers.
- Color-coded tubing and filters.
- Quick connect fittings.
- Teflon tape.
- Detailed installation manual including pictures.
- Pre and post-filters need to be changed every 6-12 months. Alkaline filter and reverse osmosis membrane last a minimum of 2 years.
- Keeps maintenance requirements at a bare minimum.
- Average annual filter replacement cost: $150-225 USD.
- USWS customer service is A+.
- The system is warranted for 5 years.
Cons
- Our only complaint is price which is naturally higher due to this alkaline under sink water filter being American-made and warranted for 5 years.
- Also applies to replacement filters.
- We are missing NSF certifications with contaminant reduction rates.
Our Rating
- Filtration Performance: 5.0/5.0
- Filter Life: 5.0/5.0
- Price: 4.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 5.0/5.0
Best for
The USWS All American is best for people who want an under sink alkaline water filter that’s Made in USA, easy to hook up and use, and highly effective.
2. Best Non-RO: Crystal Quest Alkaline Under Sink Water Filter System
If you prefer a non-RO alkaline under sink water filter system, we definitely recommend the Crystal Quest.
It uses a variety of filter media for broad contaminant removal and increases your water’s mineral content and alkalinity with the help of ionizing media. The end result: Great-tasting and filtered alkaline drinking water – we like!
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Crystal Quest Alkaline Under Sink Water System |
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| Price: | $$ |
| Filter Type: | 3 Stages, Separate Faucet |
| Water pH: | Not Specified |
| Minerals: | Calcium + Magnesium Carbonates |
| Annual Cost: | ~$75-140 |
|
Overall Rating: 5.0/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
Get 5% Off! Use Code: |
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Other Specs
- Model: CQE-US-00340
- Last Price: $256.80
- Filter Media/Process: 5-Micron Carbon Block, GAC + Catalytic Carbon + KDF + Ion Exchange + Mineral Balls, Mineralization Filter
- Flow Rate: 0.3-0.5 gpm
- Filtering Capacity: 1-3 Years
- WxHxD: 15″x14″x5″
- Water Temperature: 40-90 °F
- Water Pressure: 20-60 psi
- Fitting: 1/4″
- Warranty: 1 Year
Key Features & Pros
- Greatly improves the taste of water you can use for drinking & cooking.
- We have a 3-stage filter process:
- First a 5-micron carbon block filter cartridge traps silt, sand, dirt, and sediment. It further adsorbs chemicals like volatile organic compounds, pesticides, industrial solvents as well as chlorine and its disinfection byproducts.
- The proprietary SMART filter cartridge combines granular activated and catalytic coconut-shell carbon, two types of KDF, and anion exchange resin. This blend of filter media removes or reduces all the different contaminants that might be lurking in your water supply: Chlorine (99.9%) and chloramine, THMs, heavy metals such as lead, pesticides and herbicides – you name it. Ceramic and tourmaline balls already maintain a more alkaline pH at this point.
- The alkalizing water filter contains natural calcium and magnesium carbonates. This adds healthy minerals to your water and further increases water pH levels.
- A faucet and all necessary installation hardware are included.
- All in all, the Crystal Quest under sink alkaline filter is easy to install and use.
- Choose between T-valve (flex tubing) or saddle valve (copper tubing) depending on your plumbing setup.
- The under sink filter system is easy to maintain. Carbon block and alkaline filter last 12 to 18 months. The SMART filter cartridge should be good for up to 3 years.
- We estimate around $75 to $140 USD in annual cost. A real bargain!
Cons
- If you don’t use a licensed plumber for installation, the 1-year product warranty will void.
- No NSF certifications.
- 0.3-0.5 gallons per minute flow rate is slow.
Our Rating
- Filtration Performance: 4.5/5.0
- Filter Life: 5.0/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 5.0/5.0
Best for
The Crystal Quest alkaline filter is best for people who want a standard water filtration system for broad contaminant removal that provides alkaline drinking water.
3. Best for Tankless Alkaline RO Filtration: Frizzlife PD600-TAM3
As an alternative to the under sink alkaline water filter by US Water Systems, check out the Frizzlife PD600. It’s another reverse osmosis system, although this one features a tankless design!
Frizzlife PD600-TAM3 |
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| Price: | $$$ |
| Filter Type: | Tankless RO, 4 Stages |
| Water pH: | >7.5 |
| Minerals: | Not Specified |
| Annual Cost: | ~$105 |
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Overall Rating: 4.5/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
Get $80 Off! Use Code: |
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Other Specs
- Model: PD600-TAM3
- Last Price: $469.99
- Filter Media/Process: Sediment + Carbon Filter, RO, Remineralization
- Flow Rate: 0.41 gpm
- Membrane Rating: 600 gpd
- Recovery Rate: 60%
- Filtering Capacity: 1-2 Years
- Water Temperature: 39-100 °F
- Water Pressure: 20-80 psi
- Fitting: 3/8″
Key Features & Pros
- According to reviewers, filtered water tastes amazing.
- We have a 2-in-1 composite filter (pleated polypropylene sediment filter + activated carbon block) followed by a semipermeable reverse osmosis membrane that remove bad taste and odor, chlorine & chloramine, TDS, chromium 6, cadmium, lead, radium, cyst, arsenic, fluoride, PFOA & PFOS, and other water pollutants for healthy drinking water.
- The alkalinization and remineralization filter adjusts water pH to at least 7.5. It also restores minerals.
- An internal pump and the high-capacity membrane achieve a fast water flow rate of 0.41 gpm.
- It only takes about 10 seconds to fill a large glass with RO water.
- Due to high pressure, wastewater production is as low as 1 gallon wasted for every 1.5 gallons filtered.
- Much better than what any standard RO system can provide.
- Tankless design saves space.
- Stainless steel faucet with brushed nickel finish is included.
- Smart display panel tells output water TDS and remaining filter life.
- Constantly monitors water quality.
- Reminds you when to change filters.
- Very simple installation due to tankless design.
- Single-turn quick filter replacements. Stage 1 and 3 last 12 months. Membrane is good for 2 years. Convenient!
- $105 USD in annual replacement cost which is affordable.
- No need to shut power off.
- Frizzlife has a 30-day-trial return policy offering a full refund.
Cons
- Again, we would have preferred NSF testing/certifications providing contaminant reduction rates.
- We couldn’t find information on product warranty.
Our Rating
- Filtration Performance: 4.5/5.0
- Filter Life: 5.0/5.0
- Price: 4.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 4.5/5.0
Best for
The Frizzlife is best if you prefer reverse osmosis water purification combined with a tankless system design.
4. NU Aqua Platinum Series 6 Stage Alkaline System
Next, we will take a look at the NU Aqua Platinum Series 6 Stage Alkaline System. Its most important advantage is the really low price tag.
NU Aqua Platinum Series 6 Stage Alkaline System |
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| Price: | $$ |
| Filter Type: | RO, 6 Filter Stages |
| Water pH: | Not Specified |
| Minerals: | Not Specified |
| Annual Cost: | ~$125-155 |
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Overall Rating: 3.5/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
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Other Specs
- Model: WU-100GPD-NP-ALK-BDL
- Last Price: $209.95
- Filter Media/Process: Sediment + Carbon Pre-Filters, RO, Carbon Post, Remineralization
- Membrane Rating: 100 gpd
- Filtering Capacity: 0.5-1.5 Years
- Tank: 3.2 gal
- Water Temperature: 40-100 °F
- Water Pressure: 45-80 psi
- Fitting: 1/2″ or 3/8″
- Warranty: 3 Years
Key Features & Pros
- A ridged sediment filter traps visible particle matter.
- GAC removes chlorine, pesticides, color, bad taste, and odors.
- The carbon block filters chlorine, VOCs, organic chemicals, giardia & crypto, iron, and manganese among other stuff.
- The semipermeable membrane rejects sodium, copper, chromium, lead, arsenic and all other remaining water contaminants.
- A carbon post-filter is used to give the water a final polish, removing any bad taste or smell originating from the storage tank.
- Last but not least, an alkaline remineralization filter adds beneficial minerals and makes the water alkaline.
- Uses bio ceramic, tourmaline, calcite, Maifan, and ORP balls to neutralize body acidity, improve immunity and your body’s ability to absorb essential nutrients, increase blood oxygen levels, and slow down aging – according to manufacturer.
- The 100-gpd TFC membrane provides for faster water flow, so no need to wait long for water to get purified.
- Filter housing wrench, TDS meter, leak stop valve (prevents leakages protecting your property), and chrome faucet are part of the deal.
- Different filter stages last 6 months to 1.5 years not requiring too much of your time or effort. At roughly $125-155 USD the costs are manageable.
- 120-day risk-free money-back guarantee. Try the NU Aqua for up to 4 months and send it back for a full refund if you are not satisfied.
- Only when bought on nuaquasystems.com.
- 3-year warranty for peace of mind.
Cons
- The 3.2-gallon storage tank is a tad smaller than what you get with the USWS system.
- You get a step-by-step installation and maintenance guide, but instructions could do with an improvement.
- Still, you don’t need to hire a plumber. DIY install shouldn’t take more than 1-2 hours if you are handy with tools.
- No tested/certified contaminant reduction rates.
Our Rating
- Filtration Performance: 3.5/5.0
- Filter Life: 3.5/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 3.5/5.0
Best for
The NU Aqua under sink filter is ideal if you like the idea of an extended product trial period.
5. Best Budget Option: Express Water ROALK5D Under Sink Alkaline Water Filtration System
Our next under sink alkaline water filter review features the Express Water ROALK5D.
It uses various stages for water filtration and multiple types of mineral rocks to provide alkaline drinking water.
Express Water ROALK5D |
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| Price: | $$ |
| Filter Type: | RO, 6 Filter Stages |
| Water pH: | Not Specified |
| Minerals: | Potassium, Calcium, Magnesium & Other |
| Annual Cost: | ~$120 |
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Overall Rating: 4.0/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
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Other Specs
- Model: ROALK5D
- Filter Media/Process: Sediment Pre, 2x Carbon Pre, RO, Carbon Post, Remineralization
- Membrane Rating: 50 gpd
- Recovery Rate: 25-50%
- Filtering Capacity: 0.5-1.0 Year
- Tank: 3.2 gal
- WxHxD: 15.5″x18″x5″
- Water Temperature: 40-100 °F
- Water Pressure: 45-80 psi
- Fitting: 1/2″ or 3/8″
- NSF Testing: 42, 58, 401
- Warranty: 1 Year (Limited)
Key Features & Pros
- We have a 5-stage filtration process. Sediment and carbon pre-filters remove dirt and chemicals. The RO membrane eliminates heavy metals, salt, minerals, and more. The carbon post-filter ensure crisp water taste.
- A sixth stage uses 5 types of minerals rocks for water alkalinization.
- Potassium, calcium, magnesium and other beneficial minerals will be added to your water.
- Oxygen content increases by up to 20 percent.
- NSF standard 42, 58, and 401 (+ EPA 524.2) testing guarantee effective removal of up to 158 water contaminants.
- VOCs most > 99.98%
- Fluoride 99.83%
- Chlorine 98.62%
- Chloramine 99.68%
- Nitrate 99.26%
- Nitrite 98.92%
- Mercury 99.85%
- Lead 99.37%
- Arsenic 98.15%
- Chromium 6 99.63%
- Pharmaceuticals most > 99%
- Semi-volatiles most >98%
- 360° swivel chrome faucet included.
- Leak detector closes water flow upon detecting moisture. Great protection.
- Quick-connect system is designed for speedy hook-up.
- You can complete the project yourself and save money on professional installation.
- Filter changes are quick and easy. All filters last 6 months, except the membrane which is good for 12 months. Cost: ~$120 USD which is acceptable.
- 1 year limited warranty.
Cons
- We read about issues with leaking.
- One user complained about bitter taste.
- The 4-gallon storage tank is a little bit smaller compared to the USWS under alkaline sink water filtration system.
Our Rating
- Filtration Performance: 4.5/5.0
- Filter Life: 3.0/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 4.0/5.0
Best for
The Express Water ROALK5D is best for people on a very tight budget.
6. Best NSF-Certified: iSpring RCC7AK Under Sink Alkaline RO Water Filter
The iSpring RCC7AK is one of a few under sink alkaline water filters that are NSF certified for contaminant reduction. However, there also have been a number of complaints about the system…
iSpring RCC7AK |
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| Price: | $$ |
| Filter Type: | RO, 6 Stages |
| Water pH: | Not Specified |
| Minerals: | Magnesium, Calcium, Potassium |
| Annual Cost: | Less Than $100 |
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Overall Rating: 4.5/5.0 ⓘRatings based on treatment process, achieved water pH, mineral composition, NSF, filter capacity, cost, our testing, user ratings, product warranty, and other factors.
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Other Specs
- Model: RCC7AK
- Filter Media/Process: Sediment Pre, GAC, Carbon Block, RO, GAC, Remineralization
- Membrane Rating: 75 gpd
- Recovery Rate: Up to 25%
- Filtering Capacity: 0.5-3.0 Years
- Tank: 3.2 gal
- Water Temperature: 40-100 °F
- Water Pressure: 45-70 psi
- Fitting: 1/2″ or 3/8″
- NSF Testing: 58
- Warranty: 1 Year
Key Features & Pros
- 5 stages of filtration + 1 mineralization & alkalinization stage provide safe and healthy alkaline drinking water.
- Stage 1: A polypropylene (PP) sediment filter traps rust, dust and other larger particles.
- Stage 2: A 5-micron granular activated carbon (GAC) filter adsorbs chlorine and other chemicals as well as unpleasant tastes and odor.
- Stage 3: A 5-micron carbon block filter reduces chloramine content. Other (harmful) chemicals are removes, too.
- Stage 4: The RO membrane filters 97-98% aluminum, 94-96% fluoride, 99% protozoa, 95-98% radioactivity, 99% asbestos, 96-98% lead, 98-99% iron, >99% viruses and bacteria, 96-98% mercury, 97-99% nickel, >90% pesticides, and 95-99% TDS (according to NSF/ANSI standard 58).
- Stage 5: A granular activated carbon filter removes residual tastes and odors.
- Stage 6: A pH filter balances pH levels and adds magnesium, calcium, and potassium.
- Filtration capacity is up to 75 gallons per day. This should be enough water even for larger households.
- A leak detector provides ease of mind. It triggers an acoustic alarm whenever it detects moisture beneath the under sink water filter.
- DIY installation possible. A written guide and helpful videos lead you. Also, all parts are included.
- Pre and post-filters last 6 to 12 months, the RO membrane 2 to 3 years. Replacement costs are extremely low (less than $100 USD).
- iSpring offers a 1-year money-back guarantee and a limited manufacturer warranty, so you are covered.
Cons
- Several users reported recurring leaks, mainly due to low-quality parts.
- Other said they had received faulty parts.
- iSpring support is based in Alpharetta, Georgia but may be unresponsive at times.
- 3.2-gallon tank (2.5-gallon water holding capacity) is small.
Our Rating
- Filtration Performance: 4.0/5.0
- Filter Life: 5.0/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 4.5/5.0
Best for
The iSpring RCC7AK alkaline under sink water filter is best if you insist on an NSF certification for TDS removal.
→ Read Our Full iSpring RCC7AK Review Here
More Reviews:
- Reviews of the Best Under Sink Water Filters
- Reviews of the Best Under Sink Water Filters for Well Water
- The Best Tankless Under Sink Water Filter System
- Reviews: Water Filter Pitchers for Well Water
- Best UV Water Filters
- Reviews of the Best Water Dispenser Filters
- Reviews of the Best Alkaline Water Filter Pitchers
- Best Whole House Alkaline Water Filtration Systems
- List with All Under Sink Water Filters Featured on BOS
System Comparison List
How do the best under sink alkaline water systems perform when directly compared?
(Mobile Hint: Swipe to Scroll)
| Model | Price | Type | Filter Process | Filter Life | Water pH | Minerals | Annually | Warranty | Additional Info |
|---|---|---|---|---|---|---|---|---|---|
| US Water Systems All American | $$$ | RO | Sediment Pre, Carbon Filters, RO, Remineralization | 0.5-5.0 Years | ~8.5-10.0 | Ca, K, Mg | ~$150-225 | 5 Years | |
| Crystal Quest Alkaline Under Sink Water System | $$ | Standard | Carbon, KDF, Ion Exchange, Mineral Balls, Mineralization | 1-3 Years | ? | Ca, Mg | ~$75-140 | 1 Year | |
| Frizzlife PD600-TAM3 | $$$ | RO | Sediment, Carbon, RO, Remineralization | 1-2 Years | >7.5 | ? | ~$105 | ? | |
| NU Aqua Platinum Series | $$ | RO | Sediment, Carbon, RO, Remineralization | 6-18 Months | ? | ? | ~$125-155 | 3 Years | |
| Express Water ROALK5D | $$ | RO | Sediment, Carbon, RO, Remineralization | 6-12 Months | ? | K, Ca, Mg | ~$120 | 1 Year | |
| iSpring RCC7AK | $$ | RO | Sediment, GAC, Carbon Block, RO, Remineralization | 0.5-3.0 Years | ? | Mg, Ca, K | Less Than $100 | 1 Year |
Buying Guide: How We Picked the Best Alkaline Under Sink Water Filter Systems + What You Need to Consider
The following are things worth considering before you go out and buy an under sink alkaline water filter system. These are also the very same criteria we focused on when picking our top products for this guide.
Filter Type: Regular or Reverse Osmosis
We like to differentiate between two types of alkaline under sink water filters:
- Regular systems
- Reverse osmosis systems
Regular alkaline under sink water filters can use a variety of filter media for contaminant removal. Such filter media include sediment filter cartridges, granular activated carbon, carbon blocks, KDF, and ion exchange resin. Each type is designed for reducing a specific set of water impurities or pollutants.
Reverse osmosis alkaline under sink systems are somewhat different. For pre and post-filtration, they usually combine some of the filter media just mentioned. In addition, they use a semipermeable reverse osmosis membrane which does the bulk of the contaminant removal.
However, an RO membrane not only removes the bad stuff, it also removes all the healthy minerals that your water contains. This is why RO purified water is mineral-deficient and tends to be slightly acidic. As such, a more powerful remineralization and alkalinization process is required in order to balance water pH and alkalinity.
By the way, both reverse osmosis and regular under sink water filtration systems can be highly effective at what they do, providing clean, safe, and great-tasting drinking water.
Filtration Process
It’s best if you go with an under sink water filter featuring multiple filtration stages.
There are exceptions, but in general, the more filter stages a system has, the more contaminants will be removed and the higher the achieved filtered water quality.
Depending on your water chemistry, you can select:
- Sediment filter – These are surface or depth filters that trap solid floating particles down to the submicron level.
- Activated carbon – Removes chlorine taste and odor and all kinds of chemicals like pesticides and VOCs.
- Ion exchange filter media – Great for reducing heavy metals such as chromium 6.
- KDF – Great against certain chemicals and water-soluble heavy metals.
- Iron filter – A dedicated iron filter may be required if you are dealing with excessive iron levels in your water.
- Reverse osmosis membrane – These membranes have a tiny pore size of 0.0001 micron. This rejects almost all contamination from salts and minerals to metals and radiologicals.
And there are many other types of filtering methods you can choose from. Ideally, you make this decision after you have tested your water and know what you are facing.
The downside to more filter stages is higher maintenance costs, a bulkier system, and possibly a decrease in output water pressure and flow.
pH and ORP
The whole point of using an under sink alkaline filter is to increase water pH levels. Any pH level above 7.0 is considered alkaline. That said, most people are probably looking for alkalinity of at least 8.0-9.0. In our opinion, you have the highest chance of achieving this by choosing a non-RO filter system (remember: RO water purification lowers water pH).
Some manufacturers also provide a range for the pH level their alkaline water filters can reach. For instance, the US Water Systems All American system is advertised to increase pH to around 8.5-10.0.
Then there is oxidation-reduction potential of water, short ORP. Alkaline ionized water has a negative ORP value, so it can act as an anti-oxidizing agent, neutralizing free radicals in your body. According to alkaline water filter vendors, this has a positive impact like a more active immune system.
NSF Standards
We prefer water filters that have been certified against NSF/ANSI standards for contaminant reduction. This is the only way to guarantee an effective filtration process. In addition, some NSF/ANSI standards also cover structural integrity and material safety.
- Standard 42 tests for the reduction of non-health-related (aesthetic) water contaminants, mainly chlorine.
- NSF Standard 53 is for the reduction of contaminants currently regulated by the EPA that have health effects. The standard covers cysts, VOCs and other chemicals, certain heavy metals, and more.
- Standard 401 is for 15 so-called “emerging compounds“. This group includes trace pharmaceuticals and pesticides/herbicides.
- Lastly we have NSF/ANSI Standard 58. This one is only for reverse osmosis systems. TDS (Total Dissolved Solids), chromium, nitrate/nitrite, arsenic, and lead are a few of the many contaminants this standard establishes minimum reduction rates for.
Water Pressure and Flow Rate
Water pressure and flow rate is particularly important with under sink water filter systems providing filtered water on demand. Because they are tankless, the filtration speed must be fast-enough to avoid long waiting times. Simply put, a water filter that takes one hour to fill a single glass of water is of no good.
We consider 0.4 to 0.5 gallons per minute a good baseline.
But even with tank-based under sink filters – most reverse osmosis systems fall under this category – output water flow rate and pressure should be above a certain level. This makes the overall filtration process more efficient, both in terms of contaminant removal and clean-to-wastewater ratio.
Installation
Installing an under sink alkaline water filter – reverse osmosis or not – yourself is not too complicated and will save you quite a bit of money.
Ideally, your new unit will feature an inline design and not come with a separate faucet, because drilling a hole in the kitchen countertop can be more difficult. Don’t worry though in case your under sink filter does indeed use an extra dispenser. With a little bit of experience you should be able to pull this off, too.
The only scenario where we advise against DIY installation is when it will void the product warranty. Here, it’s better to spend a few hundred dollars and have a professional do the setup for you.
Required Maintenance and Filter Capacity
Under sink water filters are easy to maintain for the most part. An alkaline filter stage doesn’t change that.
What tasks does maintenance involve? First and foremost, you need to replace filter cartridges according to schedule. Most last between 6 and 12 months. RO membranes can be used for up to 5 years, depending on the quality. And the alkaline filter should be good for 1 to 2 years.
You should keep in mind, however, that such filtration capacities are ideal values. They can vary depending on your water conditions and usage.
On a side note, the effort it takes to change filter cartridges largely depends on system design. Some twist on/off filters can be changed in 10 seconds without having to turn off the water supply. With other units, it takes much longer and can get pretty messy.
Cost & Warranty
You need to take into account the initial price tag of an under sink alkaline water filter, plus expenses for installation and filter replacements.
Especially the latter can start to add up in the long run. This is when longer filter lives really pay off.
As for warranty, a reputable brand should warrant its products against defects in manufacturing and workmanship for at least 1 year.
Methodology: Why Trust Us?
We are pleased to share our methodology for reviewing under sink alkaline water filters:
- Criteria – First, we crafted a list of 20 essential attributes to evaluate all products against.
- Getting started – We embarked on an extensive search, compiling a diverse list of over 16 under sink alkaline water filters available online.
- Research – We studied manuals, descriptions, lab reports, certifications, and other sources. We also assessed the support and dedication from filter brands. This process narrowed down our list to the top 10 systems worthy your attention.
- User opinions – To ensure only the cream of the crop would made the cut, we relied on genuine user feedback from reputable sites.
- Hands-on testing – We installed a selection of the 6 remaining systems onto our water supply, subjecting each filter to rigorous evaluation from every angle. Ease of installation, filter priming, flow rates, water pH and taste, and so on. Each filter underwent a minimum of 3 weeks of flawless performance testing.
- Science – To further enhance our findings, we partnered with independent laboratories like Tap Score for extensive lab testing. We wanted to know real-life contaminant reduction rates.
- Final showdown – After a thorough journey, we created this comprehensive buying guide allowing you to confidently make an informed purchase decision.
Rest assured, our information and ratings are honest and unbiased. We have subjected our content to professional fact-checking.
More on Under Sink Alkaline Water Filters
Further Reading:
What Is an Alkaline Under Sink Water Filter and How Does It Work?
An alkaline under sink water filter is a piece of home equipment that gives you access to filtered alkaline drinking water.
As the name suggests, it gets installed under a kitchen or bathroom sink and provides clean alkaline water at a single point of use.
Most units use more than one filter stage to remove as many water contaminants as possible and increase water pH and mineral content.
Who Needs Alkaline Water Filters?
There are several scenarios one can think of for when an alkaline water filter can make a great addition to your home:
- Your water supply quality is solid but the water is too acidic. This is rare, but it can happen.
- Your water supply is full of organic and inorganic substances posing a health threat. In order to protect yourself, you can install an alkaline water filter.
- Your water tastes bitter or has a strong chlorine stench and you want to improve overall water aesthetics. An alkaline water filter is ideal here. It not only removes unpleasant taste and odor, it also provides for a more pristine taste due to added mineral content.
- Although you are not much worried about overall water quality, you prefer alkaline drinking water for one or more reasons.
Advantages and Disadvantages of Using an Under Sink Alkaline Water Filter
What are the advantages and disadvantage of using under sink alkaline water filters?
Reduced Contaminants
Clearly one of the main advantages is less to no water contamination. Public and private water quality has been deteriorating in the US in recent years. Adding an extra layer of protection to your drinking water certainly won’t hurt.
Better-Tasting Water
For one, filtered water tastes a lot better. What’s more, water enhanced with minerals like calcium, magnesium, and potassium increase water aesthetics even further. It feels like drinking straight from a mountain spring.
Added Minerals
The extra mineral dose also adds to your daily nutritional intake. For instance, around 20% of the calcium we need to ingest on a daily basis should come from the water we drink. But what if your water lacks calcium?
Higher Water pH
Advocates swear on the health benefits of drinking alkaline water. They include:
- Anti-aging properties
- Immune system support
- Losing weight
- Lower risk of cancer
- Better hydration
- Healthier skin
- Detoxing
Cheaper Than Bottled Water
Doing your own water filtration at home is so much more cost-effective than buying bottled water all year round.
In fact, bottled water costs up to 2,000 times as much as tap water.
So why not save hundreds if not thousands of dollars on an annual basis by simply installing a water filter in your home?
Easy to Use
Alkaline under sink water filters, actually under sink filters in general, are easy to use. Once installed, all you need to do is open the dispenser whenever you feel thirsty.
What about filter replacements? These only need to be done once or twice a year and are a piece of cake.
Scientific Evidence Missing
The main disadvantage of alkaline water filters is that there still is lack of proven scientific research in regards to the claimed health benefits of alkaline drinking water.
Possible Side Effects
Healthline even mentions potential negative side effects. These include:
- Lowered stomach acidity. Stomach acidity is needed to kill pathogens and prevent them from entering your bloodstream.
- Gastrointestinal issues.
- Skin irritations.
- Metabolic alkalosis. This is a more serious condition causing vomiting, nausea, muscle twitching, confusion, and other issues.
Extra Cost
Using an alkaline water filter versus a regular one means an extra filter stage which adds to the purchase price and maintenance cost.
Under Counter Alkaline Filters vs. Countertop Units
Under sink and countertop alkaline water filters have both similarities and differences.
1. The Filter Process
This is where both filter types are quite similar. They come as multi-stage and as single-stage systems. We also find inline and reverse osmosis filters in both groups.
2. Filtration Capacity
There are hundreds of filter models currently available. One will find low and high filter capacities in either category.
3. Filter Replacements
The actual filter replacement process is quite similar in under sink and countertop water filters: You open the filter sump, remove the old cartridge, insert a new one, and reattach the filter housing.
4. Size
When it comes to size, under sink vs countertop water filter can make a big difference. Countertop water filters are usually small and compact so they don’t occupy too much space on the kitchen counter.
In contrast, under sink water filters can be larger in size since they are stored in a cabinet.
5. Installation
Countertop water filters are installation-free, meaning they either can be connected to a faucet or tap within minutes, or they are autarchic.
Under sink water filters on the other hand require a direct plumbing connection.
Alkaline Water vs. Filtered Water vs. Plain Water
What’s the difference between alkaline, filtered, and plain (tap) water?
- Strictly speaking, alkaline water is any water with a pH above 7.0. In our context, however, alkaline water is water that has been alkalized for health benefits. Drinking alkaline water is associated with slowed aging, better immune system, healthier skin, and more. Above that, alkaline water often contains a higher amount of beneficial minerals.
- Filtered water is private well or tap water that has undergone filtration in order to remove contaminants and impurities. This is done for two reasons. First, to remove potentially harmful elements that could damage your health when ingested. And second, to improve the taste and smell of the water.
- Plain water is ordinary tap water or well water without any additional treatment. It may have an off-taste or unpleasant odor due to contamination. And it may hold pollutants that could cause you harm.
Frequently Asked Questions (FAQ)
- Does alkaline water need to be filtered?
Sometimes yes, sometimes no. It depends on its overall chemistry. If there are harmful contaminants in the water, then it should be filtered before consumption. Also, some chemicals and other substances can mess with the taste and odor. - How long does an alkaline water filter last?
The alkaline filter cartridge itself should last about 1 to 2 years, depending on your water usage. An alkaline water filter system can last forever if you replace the filter elements regularly and perform occasional cleaning. - What happens if you filter alkaline water?
Unwanted pollutants will be removed, so the quality increases. You just shouldn’t use a reverse osmosis system for this. RO water purification removes minerals and lowers water pH. - Can you drink alkaline water every day?
There are mixed opinions about this. Alkaline water is considered safe for the most part, but too much can cause issues.
I hope this list of the best under sink alkaline water systems was helpful. Questions? Ask away!
And keep in mind: We’ll add new alkaline under sink water filter reviews occasionally. So come back for more!
About the Author Gene Fitzgerald
