5 Best Inline Under Sink Water Filters (*Update 2024)
Written by: Gene Fitzgerald // Expert Fact-Checking: Buddhini Dolapihilla, MBSS // Last Updated: Jan 31, 2024
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Top Pick: What’s the Best Inline Under Sink Water Filter?
The best inline under sink water filter in 2024 is the Clearly Filtered 3-Stage, because it has proven to remove 200+ water contaminants, it’s very easy to install and maintain, it uses long-lasting filter cartridges (up to 2,000 gallons), and it’s backed by a 1-month money-back guarantee and a lifetime warranty.
Are you tired of playing the guessing game when it comes to finding the perfect inline under sink water filter? We feel you! With so many options out there, it’s like navigating a maze just to quench your thirst for clean and refreshing water. But fret not, because we’re here to be your water filtration superheroes!
We’ve gone above and beyond to bring you the most comprehensive guide to inline under sink filters. We’ve put on our lab coats, strapped on our testing goggles, and meticulously evaluated over 14 systems currently on the market. It’s been a whirlwind of research, testing, and comparing. And we’re constantly updating and upgrading our recommendations to ensure you get the latest and greatest in water filtration technology. Let’s go!
Contents
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No Time to Read? Check Our List of the Best Inline Under Sink Water Filters!
| Product | Details | |
|---|---|---|
 Best Pick: Clearly Filtered 3-Stage |
Overall Rating: 5.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
Get 10% Off! Use Code: |
Price: $$$ Water Flow Rate: Not Specified Filter Life: 2,000 Gallons NSF Standards: 42, 53, 401 Yearly Maintenance Cost: $440 Read Review: Click Alexa’s Video Review: Click |
 Best Budget Option: Epic Smart Shield |
Overall Rating: 4.5/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
Get 20% Off! Use Code: |
Price: $ Water Flow Rate: 1.25 Gallons Per Minute Filter Life: 651 Gallons NSF Standards: 42, 53, 401 Yearly Maintenance Cost: $115 Read Review: Click Alexa’s Video Review: Click |
 Best for Customized Water Filtration: Hydroviv |
Overall Rating: 4.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
|
Price: $$ Water Flow Rate: Not Specified Filter Life: 720 Gallons NSF Standards: 42, 53 Yearly Maintenance Cost: ~$230 Read Review: Click |
 Best for Microorganisms: ProOne FS10 |
Overall Rating: 4.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
|
Price: $$$ Water Flow Rate: 1 Gallon Per Minute Filter Life: 1 Year NSF Standards: 42, 53, 401, P231 Yearly Maintenance Cost: ~$200 Read Review: Click |
Inline Under Sink Water Filter Reviews
Our Top Picks
- Clearly Filtered 3-Stage – Best for Broad Contaminant Removal
- Epic Smart Shield – Best for Low Budgets
- Hydroviv – Best for Customized Water Filtration
- ProOne FS10 – Best for Waterborne Pathogens
- Frizzlife SK99
1. Best: Clearly Filtered 3-Stage Inline Under-the-Sink Water Filter System
In our opinion, the best inline under sink water filter in 2024 is the Clearly Filtered 3-Stage. It’s hands down the best at removing the most types of water contaminants providing water that is much safer and healthier to use.
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Clearly Filtered 3-Stage Under-the-Sink Water Filter System |
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| Price: | $$$ |
| Flow Rates: | Not Specified |
| Filtration Capacity: | 2,000 gal |
| NSF Testing: | 42, 53, 401 |
| Annually: | $440 |
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Overall Rating: 5.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
Get 10% Off! Use Code: |
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Alexa’s Video Review
As part of the BOS team, Alexa has installed and tested the Clearly Filtered Under-the-Sink Water Filter System in her own home and with her own hands. She has used the system for several weeks to gather genuine first-hand experience. And most importantly, Alexa has documented the entire process, including her findings and personal opinion, in the video below:
Other Specs
- Model: CF-UTSF
- Last Price: $550.00
- Filter Media/Process: Coconut Carbon Pre-Filter, Proprietary Blends
- Filter Stages: 3
- WxHxD: 15″x15.4″x3.1″
- Weight: 6.9 lbs
- Water Temperature: 38-85 °F
- Fitting: 3/8″
- Warranty: Lifetime (Limited)
Key Features & Pros
- Made in the USA.
- 3-stage inline under sink water filter system uses the following:
- Granular activated carbon removes chlorine/chloramine, poor taste and odor, turbidity, VOCs (up to 99.9%), pesticides, and various other chemical contaminants.
- A proprietary filter media stage removes heavy metals like chromium (99.4%) and lead, pesticides/herbicides (up to 99.9%), PFAS (99.6-99.8%), radiological elements, and more.
- The final filter is another proprietary stage designed to target both arsenic and fluoride.
- The system is tested against NSF standards 42, 401, and 53.
- Tested against over 230 contaminants – some of the most exhaustive testing we have seen.
- Essential minerals won’t be removed during the filtration process.
- Inline design is simple and easy to install using your existing plumbing lines and faucet.
- Installation can be accomplished in less than 15 minutes without the need for plumbing or power tools.
- Can be installed horizontally, vertically, or even leaning on its side for maximum space saving.
- Nonpermanent installation makes the system ideal for renters as well as homeowners.
- Connects directly to the under-sink cold water supply line.
- Stainless steel inlet and outlet houses come included.
- Modular filter cartridges are simple and quick to change without the need for tools – simply twist, remove, and replace.
- High capacity 2,000 gallons or one-year life.
- Save 10% on replacement filter costs when you sign up for autoship.
- 30-day satisfaction guarantee or your money back.
- Limited lifetime warranty.
Cons
- Expensive when compared to other water filter systems due to US manufacturing and thorough testing.
- Replacement filter cost is high, even when considering the 10% discount with the autoship program.
- A 25 to 35 percent reduction in water pressure from your faucet can be expected.
Our Rating
- Filtration Performance: 5.0/5.0
- Filter Life: 5.0/5.0
- Price: 4.0/5.0
- Maintenance Cost: 4.5/5.0
- Overall: 5.0/5.0
Best for
The Clearly Filtered 3-Stage Under-the-Sink Water Filter System is the best overall choice when it comes to inline under sink filters without separate faucets.
→ Check the Full CF 3-Stage System Review
2. Best for Small Budgets: Epic Smart Shield Inline Under Sink Water Filter
The best inline under sink water filter for people on a smaller budget is the Epic Smart Shield!
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Epic Smart Shield Inline Under Sink Water Filter |
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| Price: | $ |
| Flow Rates: | 1.25 gpm |
| Filtration Capacity: | 651 gal |
| NSF Certifications: | 42, 53, 401 |
| Annually: | $115 |
|
Overall Rating: 4.5/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
Get 20% Off! Use Code: |
|
Alexa’s Video Review
Being an integral member of the BOS team, Alexa has ordered and tested the Epic Smart Shield Under Sink Water Filter at home. She shares her hands-on experience of installing and using the system in the video below:
Other Specs
- Model: Epic Smart Shield
- Last Price: $135
- Filter Media/Process: Carbon Block
- WxHxD: 4.25″x19.75″x4.5″
- Water Temperature: 33-100 °F
- Water Pressure: 40-120 psi
- Fitting: 3/8″ NPT
- Warranty: Lifetime
Key Features & Pros
- Made in the USA.
- The reasonable price point makes the system an excellent budget option.
- Can be used with either well supplied water or municipal supplied water.
- Areas with high levels of sediment in the water in addition to all well water users are advised by the manufacturer to install additional 5-micron pre-filtration to prevent clogging of the main filter.
- The activated coconut carbon block filter system will remove over 70 common contaminants including:
- Chlorine taste and odor (95.5%), chloramine (95.5%), particulates, lead (>99.3%), cysts (>99.99%), VOCs (99.6%), mercury (>96.6%), asbestos (>99%), and many more.
- Tested and certified against NSF standards 53, 42, and 401.
- Installation is simple and easy – typically taking less than 20 minutes to complete no matter your level of DIY and/or plumbing experience.
- Inline design and quick connect fitting make installation a breeze.
- While the system has an inline design and will operate with your normal faucet, an optional dedicated polished chrome faucet is also available.
- The average filter capacity is 1 year or approximately 650 gallons, whichever comes first.
- Annual filter replacement costs come to just $115 (or 20% less when you subscribe to the manufacturer’s ‘Clean Water Club’).
- Epic is committed to recycling and will provide you with a brand-new filter for no cost when you send in three used filters.
- Lifetime warranty plus return policy.
- Knowledgeable and responsive customer service.
Cons
- The flow rate is decent at 1.25 gallons per minute, but you may notice some drop off in terms of water pressure.
Our Rating
- Filtration Performance: 4.5/5.0
- Filter Life: 4.0/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 4.5/5.0
Best for
The Epic Smart Shield is the best budget inline under sink water filter without a separate facet.
→ Get Our Full Epic Smart Shield System Review
3. Best for Customization: Hydroviv Under Sink Water Filter
What sets this under sink direct connect water filter apart is the fact that it comes with a filter element that’s customized to your water supply quality and conditions (learn more below).
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Hydroviv Under Sink Water Filter |
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| Price: | $$ |
| Flow Rates: | Not Specified |
| Filtration Capacity: | 720 gal |
| NSF Certifications: | 42, 53 |
| Annually: | ~$230 |
|
Overall Rating: 4.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
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Other Specs
- Model: Hydroviv Under Sink Water Filter
- Last Price: $233.32
- Filter Media/Process: Varies
- WxHxD: 6″x14″x6″
- Fitting: 3/8” NPT
- Warranty: 1 Year
Key Features & Pros
- Made in the USA.
- The manufacturer uses a unique approach that involves tailoring a specific filter cartridge to your needs based on available water databases and assessments.
- The filter will target the contaminants likely to be present in your water based on publicly available data.
- Since there are many cartridge systems available with differing filter media, the exact filtration process will differ from one system to another.
- The systems can potentially remove lead, arsenic, chlorine, mercury, chromium 6, cysts, disinfection byproducts, pharmaceuticals, PCBs, PFAS, VOCs, and more.
- Many of the Hydroviv systems feature NSF certifications – including standards 53 and 42.
- Like other inline filter systems, installation is simple and can typically be accomplished in just 15 minutes or so.
- Detailed installation instructions and video are included.
- Hydroviv filter systems feature a single filter stage – making them very easy to maintain.
- 720-gallon filter capacity.
- Most systems require cartridge replacement every 6 to 12 months.
- A typical filter costs $115 – so the annual cost would be between $115 and $230.
- The manufacturer offers a 30-day money-back satisfaction guarantee.
- 1-year limited warranty on the system.
Cons
- While the tailor-made water filter system is interesting, the manufacturer bases it on public water data rather than real-life testing. This means certain contaminants may be missed, especially ones like lead or copper that can leach from old plumbing.
- Hydroviv doesn’t provide any information about the specific filter media contained in their systems.
- The systems only come with a single filter stage, which may not be sufficient for situations with highly contaminated water.
Our Rating
- Filtration Performance: 4.5/5.0
- Filter Life: 4.5/5.0
- Price: 4.0/5.0
- Maintenance Cost: 4.0/5.0
- Overall: 4.0/5.0
Best for
Overall, the Hydroviv is the best choice when it comes to a customizable inline under sink water filter.
→ Full Review of Hydroviv Under Sink Water Filter
4. Best for Microorganisms: ProOne FS10 Inline Under Counter Water Filter
Dealing with microorganisms in your water? Check out the ProOne FS10!
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ProOne FS10 Inline Under Counter Water Filter |
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| Price: | $$$ |
| Flow Rates: | 1 gpm |
| Filtration Capacity: | 12 Months |
| NSF Testing: | 42, 53, 401, P231 |
| Annually: | ~$200 |
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Overall Rating: 4.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
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Other Specs
- Model: PM-FS10
- Last Price: $388.95
- Filter Media/Process: Electro Absorption, Infused Microporous Foam Disks, Catalytic Carbon
- WxHxD: 7.25″x18.5″x7.25″
- Weight: 12 lb.
- Water Temperature: 41-100 °F
- Water Pressure: 20-80 psi
- Fitting: 3/8”
- Warranty: 2-Year Limited
Key Features & Pros
- This multi-stage water filter uses several different filter methods (ProMax FULL SPECTRUM Hybrid filter technology) to remove a wide array of water contaminants.
- Using positive electrical charge nonwoven electroabsorptive technology will remove a broad spectrum of submicron particulates, pharmaceuticals, pathogens, and even microbial debris.
- Multiple layers of porous foam disks work together to remove varying contaminants at each layer.
- Catalytic granular activated carbon improves taste and odor and targets organic contamination.
- Together, the above filter stages will effectively remove over 220 contaminants including fluoride, heavy metals such as lead (up to 99.9%), water disinfectants, VOCs, SVCs, inorganic non-metallics, pesticides (99.9%), herbicides (99.9%), pharmaceuticals, PFOS/PFOA, and microorganisms (up to 99.9999%).
- Independently tested to NSF/ANSI Standards 53, 42, P231, and 401.
- Installation is no more difficult than with other inline under sink filter systems.
- Can be installed inline or used with an optional faucet.
- Installation kit includes mounting bracket, filter wrench, lead-free fittings, and 3/8” braided flex hose.
- Maintenance requirements are also on the low end, with the filter lasting approximately 1 year.
- The annual filter cost is fair at approximately $209.95.
- Standard-sized 4.5 x 10-inch cartridges mean you can replace the cartridge with any standard cartridge should you wish to swap for a different filter.
- BPA-free materials.
- 2-year limited manufacturer warranty.
Cons
- The system is lab-tested to NSF standards, but as it’s not officially certified there is no easy way to verify these claims.
- The recommended flow rate is 0.2 to 1 gallon per minute, which on the lower end is too low to be practical. The reported lab results were probably tested with these flow rates, which allows for a longer contact time with the filter media. In reality, this is too low for normal use, so the reduction rates appear to be somewhat massaged – this is pure speculation from our end!
Our Rating
- Filtration Performance: 4.0/5.0
- Filter Life: 5.0/5.0
- Price: 4.0/5.0
- Maintenance Cost: 4.5/5.0
- Overall: 4.0/5.0
Best for
The ProOne FS10 Under Counter Water Filter is the best inline system for microorganism removal.
5. Frizzlife SK99 Inline Under Sink Water Filter System
Our final review features the SK99 by Frizzlife. It’s another budget-friendly option designed for basic tap water treatment.
Frizzlife SK99 Inline Under Sink Water Filter System |
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| Price: | $ |
| Flow Rates: | 2 gpm |
| Filtration Capacity: | 3-18 Months |
| NSF Certifications: | 42, 53 |
| Annually: | ~$50-100 |
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Overall Rating: 4.0/5.0 ⓘRatings based on filter effectiveness, NSF standards, service life, price and annual cost, product warranties, first-hand experience, user ratings, and other factors.
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Gallery
Other Specs
- Model: SK99
- Last Price: $99
- Filter Media/Process: Sediment (5-10 Microns), Activated Carbon Block (3-5 Microns), Activated Carbon Block (0.5 Microns)
- Filter Stages: 3
- WxHxD: 14.5″x14.1″x4.7″
- Water Temperature: 38-100.4 °F
- Water Pressure: 20-80 psi
- Fitting: 3/8″
- Warranty: 12-18 Months
Key Features & Pros
- Simple but effective three-stage inline under sink filter system:
- Stage 1: A 5 to 10-micron polypropylene sediment filter filters out rust, dirt, sand, and other large particles that could clog the later filter stages.
- Stage 2: Extruded carbon block filter stage to eliminate chlorine/chloramine, sediment, poor taste and odor, and other organic contaminants.
- Stage 3: A 0.5-micron carbon filter block further removes chlorine, chloramine, cysts, VOCs, other organic contaminants, and heavy metals like mercury, lead, and cadmium.
- NSF certified to standards 42 and 53 for the removal of chlorine, poor taste and odor, sediment, lead, and cysts.
- The flow rate of 2 gallons per minute is more than sufficient and won’t cause pressure issues.
- Will fill an 11 oz cup in just 3 seconds.
- Well-priced for a three-stage system.
- The compact size allows for installation in tight spaces.
- Installation is simple and easy and can be completed in under 15 minutes in most cases with basic household tools.
- The installation kit comes with braided metal hoses, which reduces the chances of leaking.
- The direct-connect version allows for tool-free installation.
- Detailed instruction installation video included.
- Maintenance requirements are low as with other inline filters.
- Twist-in cartridges allow for replacement in just 3 seconds.
- The first stage should be changed every 3 to 6 months, the second stage every 6 to 12 months, and the third stage every 12 to 18 months.
- Annual maintenance costs are just $50 to $100.
- The system comes with a 12 to 18-month-long manufacturer warranty.
Cons
- While there are three separate filter stages, there isn’t much variety in filter media. One sediment pre-filter and two carbon stages mean the system can only remove a narrow range of contaminants.
- NSF certifications are only for few specific contaminants.
- Non-standard-sized filter cartridges mean you can’t go with off-brand filters to cut costs or change filter media.
Our Rating
- Filtration Performance: 4.0/5.0
- Filter Life: 4.0/5.0
- Price: 5.0/5.0
- Maintenance Cost: 5.0/5.0
- Overall: 4.0/5.0
Best for
The Frizzlife SK99 Inline Under Sink Water Filter System is ideal for removing contaminants common to municipal water on a budget.
→ Full Review of the Frizzlife SK99 Under Sink Water Filter System
More Reviews:
- Most Effective Under Sink Water Filters
- Top Recommended Under Sink Well Water Filters
- What’s the Best Single-Stage Under Sink Water Filter?
- The Best Under Sink Hot and Cold Water Filters
- These Are the Best Inline Water Filters for Well Water!
- Tankless Under-the-Sink Filter Reviews
- Reviews of Under Sink Carbon Water Filters
- List with All Under Sink Water Filters Featured on BOS
Comparison List
(Mobile Hint: Swipe to Scroll)
| Model | Price | Filter Process | Filter Stages | Flow Rates | Filtration Capacity | NSF | Annually | Warranty | Additional Info |
|---|---|---|---|---|---|---|---|---|---|
| Clearly Filtered 3-Stage Under-the-Sink Water Filter System | $$$ | GAC, Proprietary Blends | 3 | Not Specified | 2,000 gal | 42, 53, 401 | $440 | Limited Lifetime | |
| Epic Smart Shield Inline Under Sink Water Filter | $ | Activated Carbon Block | 1 | 1.25 gpm | 651 gal | 42, 53, 401 | $115 | Life | |
| Hydroviv Under Sink Water Filter | $$ | Varies | 1 | Not Specified | 720 gal | 42, 53 | ~$230 | 1 Year | |
| ProOne FS10 Inline Under Counter Water Filter | $$$ | Electro Absorption, Foam Disks, Catalytic Carbon | 1 | 1 gpm | 12 Months | 42, 53, 401, P231 | ~$200 | 2 Years (Limited) | |
| Frizzlife SK99 Inline Under Sink Water Filter System | $ | Sediment Pre, 2x Activated Carbon Blocks | 3 | 2 gpm | 3-18 Months | 42, 53 | ~$50-100 | 1-1.5 Years |
Buying Guide: How to Choose the Under Sink Inline Water Filter That’s Best for You
The following are key features worth considering when shopping for an under sink inline water filter. They will help you choose the right on for your needs and budget.
NSF Standards
NSF refers to the independent organization that establishes testing standards to measure many different types of consumer goods against, water filters being one of them.
In other words, NSF testing and certification is the best way to ensure your inline under sink water filter is removing what the manufacturer claims it will. There are a wide variety of NSF standards available here:
- NSF Standard 42 is for the removal of ‘aesthetic effects’ from your water. This refers to chlorine, chloramine, foul tastes and odors, as well as particulates.
- NSF Standard 53 pertains to the removal of ‘health effects’, which includes things like lead, mercury, radon, VOCs, asbestos bacteria, and cysts.
- NSF Standard 401 relates to the removal of ‘emerging compounds’ from water. This includes chemicals like BPA, DEET, Ibuprofen, and many more.
Filter Methods
Inline water filter systems utilize various filtration methods, depending on their intended target contaminants. The most common are carbon and sediment filters, although specialized filter types like electroabsorption and proprietary blends are also available.
Sediment filters will remove sand, silt, rust, dirt, and other particles and not much else, so they are best used in conjunction with other filter types. Carbon filters remove chlorine, foul tastes and odors, and certain organic contaminants.
Unless you already know which contaminants you’re dealing with, it’s best to get your water tested to determine exactly which you need to remove.
Number of Filter Stages
The number of filter stages typically corresponds with the degree of system effectiveness. In other words, the more filter stages, the more effective the system is at removing contaminants.
The flip side of this is that more filter stages also mean increased maintenance costs from purchasing and replacing filter cartridges.
Flow Rates
A system’s flow rate refers to its filtration speed when you open the faucet. Flow rates are typically measured in gallons per minute (gpm), and affect the speed at which you can dispense filtered water from your faucet when opened.
As inline systems use your existing faucet to dispense filtered water, too low of a flow rate can become a pain to use. Generally speaking, flow rates below 2 gallons per minute will cause some reduction in pressure, with a significant reduction below 1 gpm.
Installation and Maintenance
Generally speaking, inline under sink filters are very simple to install, as they use your existing plumbing lines and faucet. This means you won’t need to drill a hole through the sink or countertop for a new faucet or cut into any plumbing lines.
As far as maintenance is concerned, most systems require very little, with regular filter changes being the primary maintenance task. In many systems this can be accomplished without using any tools, you simply twist, remove, and replace the old cartridge with a new one.
Filter Life
Filter life refers to a filter’s total capacity before it needs to be replaced.
Manufacturers typically provide the filter capacity in the number of gallons as well as months before replacement. Keep in mind that the figure provided by the manufacturer is the filter life under ideal conditions, and the actual lifespan will vary based on your usage level and the water quality.
Space
Typically, inline water filter systems installed under a sink do not take up much space, making them good options for smaller spaces and cabinets. As these systems do not require storage tanks, the space requirements are significantly smaller than those of typical reverse osmosis units.
Nonetheless, it’s a good idea to measure the available space under your sink and ensure the filter you purchase will fit.
Budget
All inline water filters are generally on the cheaper side.
That said, when considering the cost of a filter system, be sure to factor in the annual filter replacement cost. As filter cartridges have varying lifespans, a cheaper filter cartridge with a shorter lifespan can end up costing more than a more expensive cartridge with a larger capacity.
More on Inline Under Sink Water Filters
Further Reading:
What Is an Inline Under Sink Water Filter?
An inline under sink water filter, some people might also say “under sink inline water filter”, is a system that fits under your sink and connects with your existing cold water supply line. These systems are very simple to install and maintain and allow you to dispense filtered water from your existing kitchen or bathroom faucet.
How Does a Direct-Connect Under Sink Water Filter without a Separate Faucet Work?
Direct-connect under sink water filters, so under sink water filters without their own dedicated faucet, work in the same way as other inline systems. They connect directly to the cold water inlet under your sink and your existing kitchen faucet. They go in between the source and the output improving water quality.
This eliminates the most difficult installation task required for many under sink filter systems – installation of a separate faucet – and generally means you can install one in just 15 minutes or less.
How to Install an Inline Under Sink Water Filter
As mentioned previously, installing under sink inline filters is generally very simple, but there are still a few things to consider.
The following is only a general guideline for how to install such a system. Be sure to consult your manufacturer’s warranty for the specific instructions relevant to your model.
- First, shut off the cold water supply line underneath your sink.
- Then, open the kitchen faucet to flush out the water remaining inside the water line.
- Disengage the cold water line from the outlet.
- Install the filter as per the manufacturer’s instructions inside your under sink cabinet.
- Attach the inlet hose on the filter system to the cold water line, and carefully secure it.
- Attach the filter outlet hose to the existing faucet inlet hose. Tighten.
- Open your cold water line and flush the system as per the manufacturer’s directions.
Maintenance
When it comes to maintenance, there’s very little to do other than change the filter cartridges regularly. Be sure to check your manufacturer’s instructions for how often to change the filter cartridges to keep your system running smoothly.
Once again, the specific instructions for how to change filter cartridges will vary slightly based on the specific model. Check your system’s manual for specifics.
- Shut off the cold water supply under your sink (not all models require this).
- Open your faucet to discharge any pressure and water remaining in your water lines.
- Detach the filter housing(s) from the system.
- Toss the old filter cartridges(s) aside, clean the housing(s) interior with dish soap, dry, and insert new filter cartridge(s).
- Mount and secure the filter housing(s) back to the unit head ensuring the O-rings are seated properly.
- Turn the cold water supply back and examine the system for leaks.
Advantages of Inline Under Sink Water Filters
Ease of Installation
One of the primary advantages of inline under sink water filters is their ease of installation. Whereas other filtration systems often require drilling through sinks/countertops or cutting through water lines, inline water filters hooked up under the sink don’t require any special tools to install.
Typically, all that’s needed for installation is connecting the cold water inlet to the system, and the outlet to the existing faucet.
Space Requirements
As inline filter systems don’t require storage tanks, their space requirements are significantly less than tanked systems. This makes them ideal options for smaller spaces and compact cabinets.
Maintenance
The only maintenance task generally required for inline water filters is changing the filter cartridges on schedule. When compared to tanked or RO systems that require regular cleaning/sanitizing, this represents a significant reduction in required maintenance.
Price Point
Typically, inline water filters cost less than other under sink systems such as reverse osmosis. If you’re looking for a simple system that nonetheless offers solid filtration performance, then an inline filter system is likely your best option.
Versatility
Some of the above systems are offered with optional faucets, which allow you to install the system either to your existing faucet or to a dedicated one. Additionally, as inline under sink systems are so easy to install and remove, they make great options for renters who may need to move their system shortly.
Disadvantages of Under Sink Water Filters That Get Installed Inline
Single Faucet
One limitation of inline under sink filters is their dependence on a single faucet.
As there is no storage tank to keep a reserve of water on hand, too low of a flow rate means you’ll need to wait every time you use the cold water from your faucet. This includes when you use the faucet for other things than dispensing drinking water.
Lack of Storage Tank
While the lack of a storage tank offers several advantages, it also has its drawbacks. The system will need to filter fresh water every time you open the faucet, which means low flow rates can be particularly troublesome.
Filter Life
As all cold water dispensed by your faucet will pass through the filter system, your filter capacity will be used up significantly faster than if you had a separate dedicated faucet. This means more frequent filter changes, as well as increased maintenance costs.
Reverse Osmosis
Lastly, an inline setup is not compatible with one of the most effective filtration methods available – reverse osmosis. If you wish to filter your water using reverse osmosis, then you’ll need to purchase an RO system that comes with its own faucet.
Inline Under Sink Water Filters vs Dedicated Faucet Systems
When it comes to under sink water filters, there are two primary options – those with dedicated faucets, and those that use your existing faucet (inline).
The primary advantage of installing a system to your existing faucet is its ease of installation. As there’s no need to drill holes in your sink or countertop, these systems can often be installed in just 15 minutes or less.
Systems with dedicated faucets are more difficult to install but offer more versatility, increased filter life, and you can still use your unfiltered water faucet if you need a higher flow rate.
Frequently Asked Questions (FAQ)
- What does an inline under sink water filter remove?
It depends on the filter media/method used. A sediment filter removes floating particles. Activated carbon is great for organics and bad taste and odor. Ion exchange resin exceeds at eliminating heavy metals etc. - How long does an under sink inline water filter last?
Most filter elements typically last for 6 to 12 months before they need replacement. - Can I install my inline under sink water filter myself?
Yes, you can. In fact, an inline under sink water filter is probably the easiest type of home water filter to install. - Do all inline under sink water filters directly connect to my existing water supply and faucet?
Yes, they do. If they wouldn’t, they wouldn’t qualify as inline. - Does no under sink inline water filter come with its own separate faucet?
That’s correct. Any water filter that comes with its own separate faucet is not considered inline.
How We Chose and Tested the Best Inline Under Sink Water Filters (Why Trust Us)
Here’s a glimpse into our foolproof process of reviewing inline under sink water filters:
- Step 1: We put our years of experience and research to good use by creating a list of important criteria (18 in total) to evaluate all the products.
- Step 2: We browsed the vast online market for models, ending up with a whopping 14+ options.
- Step 3: We dove deep into product manuals, descriptions, certifications, and warranties. We even had a chat with the big shots behind several well-known brands, pretending to be eager customers. That’s right, we played detective to test their support abilities.
- Step 4: With all this detective work, we narrowed down our list to 8 models.
- Step 5: To separate the real deal from the imposters, we relied on different platforms for feedback and ratings from real users. And with our detective hats still on, we ordered and installed some of the remaining 8 products on a suitable water supply – precisely following the instructions provided by each of the manufacturers. We became water wizards testing every angle, from footprint and ergonomics to taste/aftertaste and odor of the filtered water. Each system was allowed to work for a good 4 weeks.
- Step 7: It was time for the ultimate test. We conducted our own lab experiments using Tap Score, checking the real-life reduction rates of contaminants. We wanted to make sure these filters were the real deal.
- Step 8: After all the testing, we gathered our findings and presented everything in an accessible format, so you can make the best decision nice and easy.
P.S. We take pride in our independence and unbiased approach. Our information and ratings are carefully curated, and we even have a team of professionals who fact-check our content to ensure accuracy. Buddhini Dolapihilla, MBSS played a critical role in evaluating claims of contamination reduction. This involved verifying online NSF certifications and carefully examining lab reports and other test data.
About Our Ratings
We’ve rated each inline under sink water filter on a score of 1 to 5, with 5 being the highest rating.
Our evaluation is mostly based on 5 crucial factors: NSF-tested/certified contaminant reduction rates (30%), purchase and annual cost (25%), 1st hand testing and 3rd party feedback (20%), service life (15%), product support (10%).
Questions? Ask away!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.