Is Multi-Stage Water Filters Better than Single-Stage Water Filters?

Those of you who take your health seriously, understand exactly how dangerous water contamination can be. More often than not, a situation such as this requires immediate action in order to avoid serious ramifications. Bacteria can easily build up, as harmful metals leach into the water supply, or it is otherwise contaminated by chemicals. If you are a homeowner, you are most likely a little familiar with these parameters, and the risks associated with unfiltered tap water.
Certain areas of the United States suffer from higher levels of contamination than others, ranging anywhere from simple to extremely serious. In many areas, a single-stage water filtration unit is enough to provide safe drinking water, while others demand serious solutions to remove harmful chemicals and avoid health effects. When you need to eliminate contaminants on a severe scale, higher stages of filtration serve as a great resolution. This begs the question, though: How many stages are efficient enough for your water supply?

Multi-Stage Filters

A phrase such as “multi-stage filter” may seem rather complicated, and leave homeowners confused – isn’t a water filter just a filter? When it comes to stages, each filtration system utilizes cartridges corresponding to a specific stage of water filtration. Each stage within a water filter fulfills a specific role in the overall act of filtering water – especially in terms of contamination. These filter stages utilize various types of filter material in order to fulfill the role. However, this is not to say that any given stage cannot be used more than once, or appear in later or earlier stages in a system.
A Reverse osmosis filtration system is mainly comprised of two carbon block filters, offering the same filtration capabilities as the other. What’s interesting in this scenario, is that one block will be placed upstream of the RO membrane as a pre-filter, while the other is placed downstream in order to polish water of chemical residue, sometimes called a postfilter. Though they perform similar tasks, and utilize the same materials, they both fulfill separate roles completely independent from each other.
The stages in any given filtration unit are highly dependent upon the issues surrounding the tap water within the home in which they operate. Many issues can be solved through the use of a single-stage unit, while others require something serious, such as a multi-stage filter. Some of these filters integrate a single filter cartridge with a single type of media, known as a single-stage water filter system. These may come in the form of a countertop unit, inline filter, or under-sink filter, just to name a few. A single stage unit is efficient at removing contaminants that cause issues with smell and taste.
Serious contaminants require the use of a multi-stage unit, in order to remove various contaminants, heavy metals, dangerous chemicals, and more. A multi-stage filtration unit operates off of multiple filter cartridges in specific locations, containing various types of filter media. A Reverse osmosis water purification system is the most common housing of multi-stage filtration. This is why, for the most part, a RO system can be pricey to purchase and operate. However, the results are largely unmatched by any other type of water filtration.

Mixed-Media Filters VS Multi-Stage Water Filters

A mixed-media filter is a water filter utilizing a single cartridge which fully integrates multiple types of filter material. Typically, this type of filter organizes media in a layering style. Technically, this kind of water filter could be considered “multi-stage”, however, multiple stage cartridges are usually a stage-by-stage style, which is quite different from mixed-media. A multi-stage filter takes advantage of the longer contact time, as well as a larger surface area, in the media of a multi-stage. When a filter cartridge is dedicated to one type of filter media, it provides a more efficient mode of filtration. In turn this method is likely to remove or absorb higher amounts of contaminants compared to mixed-media filters.

Advantages of Multi-Stage Filters

A multi-stage water filter offers a variety of advantages compared to other styles of filtration, which often make them worth the initial investment. This kind of filter can guarantee a whole slew of benefits, but also carry a few disadvantages you may need to consider before purchasing. Here are a few of the pros and cons of a multi-stage filter:


Optimal Filtration
Homeowners have complete control over their water filtration when it comes to a multi-stage style purification unit. They can add stages, or use the fewest required. Tap water benefits from prolonged contact to filter media, since it is forced to flow through each stage one at a time. If you are looking for thorough, trustworthy water filtration, a multi-stage filtration unit is for you.
Efficient Filtration
When you use a single-stage, or even a carbon block cartridge alone, you can’t expect to remove many contaminants. When it comes to a multi-stage unit, though, it provides a wider target of substances it’s capable of removing. This ranges anywhere from solids, pesticides, herbicides, chemicals, fluoride, and much more. Many of these “invisible” contaminants pose dangers to your health, and are easily removable with a multi-stage filtration unit.


Reduced Flow Rate
Because it provides prolonged contact with each stage of filtration, a multi-stage filter offers a reduced flow rate that may make a noticeable difference. The upside to this is you can be confident in the removal of various contaminants, however, it may not be beneficial for the impatient. Depending on your desired flow rate, check the system specs for a full understanding of what to expect as far as flow rate.
PIC: faucet
Higher Cost of Overall Maintenance
Considering the amount of stages it is possible to house within a multi-stage filter system, maintenance costs can be substantially higher compared to other units. Before purchasing your unit, ensure you have calculated costs beyond the initial purchase price, or you may be met with surprise expenses. When you need an efficient method of tap water filtration, the costs of operating a multi-stage filter are well worth it in the end.

Advantages of Mixed-Media Filters

Mixed-media filters provide numerous advantages, which are worth going through. If you need to stay on a budget, and save on space, purchasing this kind of filter may be right up your alley.
Improved Flow Rate
Flow rate typically isn’t affected by the use of a single filter cartridge. When a flow rate guarantee is one of your concerns, a single-cartridge mixed-media filter system may be for you. This is because the layers of media are comprised into one cartridge, rather than multiple cartridges in a queue.
Space Saver
When you’re low on space, and need to be conservative with new installations, a single filter cartridge is a great choice. Not only do they require much less space, but it also enables you to buy cartridges before hand for storage.
Budget Friendly
Because you only need to replace one cartridge, a single-cartridge mixed-media filter requires much less maintenance when compared to multi-stage units. There are fewer cartridges to change, which means you will spend less money in the end.

Stages of Filtration

The number of stages in any given filtration unit depends completely from unit to unit. By taking the level of contamination of your tap water into consideration, you will be better equipped to determine the kind of filter media for your household. An RO system, for example, typically utilizes 5 stages of filtration. These filters integrate different types of filter media in stages, with media such as: RO membrane, sediment filter, carbon block, granular activated carbon, and more. Check with the vendor for information concerning contaminant type, as well as removal rates, in order to determine the overall efficiency. This will go great lengths in determining which filter unit will work best for your needs.

How to Choose the Best for You

Waterdrop Triple-Stage Water Filtration System

Waterdrop’s under counter water filter, when compared to a single filter system, is capable of reducing higher amounts of contaminants, with a longer overall service life. When you are short on space, the under sink water filter is a great option. By housing 3 filters, homeowners can enjoy pure, crisp water whenever desired. The initial filter effectively removes large particles, sand, and rust. The next filter is comprised of granule activated carbon, efficiently reducing bad flavors and odors, as well as chlorine. Then, a natural carbon block (and KDF filter) lowers and prevents pollutants, further improving overall water flavor and quality.
There is no need to change bottom caps, no worries of cracks and leaks, all thanks to a sealed, durable under sink water filter housing. Featuring a 6 month, 8-12 month, and 12-18 month respective lifespan, this 3-stage under counter water filter further reduces the heavy, expensive burden of filter purchases. When you need efficient water filtration, while also sticking to a budget, and conserving space, a Waterdrop 3-stage water filtration unit is for you.

What is Ultrafiltration and How Does it Work?

Ultrafiltration is a method of water filtration much unlike reverse osmosis. Also referred to as UF, ultrafiltration utilizes the pressure of a standard home water system, in order to remove contaminants by forcing water through a semipermeable membrane. Through this method, ultrafiltration is capable of removing bacteria, parasites, and viruses, while also retaining minerals found in water. While it does bear a resemblance to reverse osmosis systems, ultrafiltration is considered to be a superior method of filtration, efficient at producing mineral rich, healthy drinking water.

What Exactly is Ultrafiltraion?

Through the use of hydrostatic pressure, ultrafiltration works similarly to reverse osmosis, forcing water through a semipermeable membrane. The overall success of this process is thanks to a membrane pore size of 103 to 106 Daltons, filtering away bacteria, viruses, endotoxins, and much more. This semipermeable membrane produces purified water with a very low density of silt, once the water is forced through. Fundamentally, the process of ultrafiltration doesn’t differ from RO, or even microfiltration, aside from the molecular size retained.
This semipermeable membrane is comprised of a thin layer of material capable of separating substances through pure force. The membrane process was once considered a dependable technology for desalination. With time, membrane processes became increasingly popular for bacteria removal, as well as other microorganisms, impacting odor, flavor, and color of resulting water. As membrane production advances continue to be made, as well as with module design, there is a noticeable decline in operating costs and capital.

How Does UF Work?

The membrane material found within ultrafiltration, utilizes hollow fibers which enables water to flow through both sides of the shell. Suspended solids of high molecular weight are retained alongside solutes, as the membrane allows water and low molecular weight solutes to pass through. Aside from the variations in retained molecular sizes, reverse osmosis and ultrafiltration aren’t different fundamentally, as well as nanofiltration and microfiltration. UF is ideal for the removal of a whole slew of contaminants that are larger than the pores of the utilized membrane, especially when combined with other forms of water purification.
As ultrafiltration systems utilize hollow fiber membranes, water is better enabled to flow through for better filtration. A large surface area is presented for particle adherence, while other membranes filter in from the outside. These fiber membranes feature a high resistance to chemicals, such as chlorine and oxidants. However, the TFC RO membrane, on the other hand is incapable of tolerating chlorine.
By comparison, a reverse osmosis system features an extensive form of filtration, due to the inherently small pore size of the RO membrane. An ultrafiltration system retains beneficial minerals that RO systems would otherwise remove. The downside to this type of filtration, is that a UF system will not remove fluoride, salts, or TDS from water sources. An RO system also requires a booster pump to operate properly, in order to increase water flow. UF systems operate on a low water pressure system, so booster pumps aren’t needed.

Microfiltration, Nanofiltration, and Ultrafiltration

The big difference between four various types of membrane based filtration lies with the reduced particle size, or membrane pore size. Determining which form of filtration is best suited to your needs, is all dependent upon your current water source situation, as well as the desired water quality. For each kind of membrane filtration, simply view the spectrum of reduction utilizing the chart below.

How is Ultrafiltration Used?

Each and every type of membrane based water filtration serves a different purpose to a variety of consumers. As such, most people who appreciate minerals being retained in their drinking water, makes UF the filtration method of choice. Plus, because it wastes less water, ultrafiltration systems may be used over an RO system. For example, in areas where water is more regulated, California residences may opt for RO over UF. Someone in the Carolinas, by comparison, where they struggle with fewer dissolved minerals, may opt for UF instead of RO. Ultrafiltration is sometimes utilized to recycle water after the process of filtration, for irrigation purposes. Microfiltration is capable of removing suspended solids ranging from sediment to algae. Nanofiltration is efficient at removing heavy solids in dairy, as well as softening purposes.

What is Ultrafiltration Capable of Removing?

A fine filter found within the UF membrane is capable of reducing particles up to 5,000 times smaller than a human hair, for a reduction of 90-100% of all contaminants. Ultrafiltration may not reduce specific organics, but it can perform better through the use of a carbon block prefilter. When installed with a prefilter, consumers will notice a marked improvement in the reduction of chlorine, lead, odor, cysts, and much more. Overall, you can also expect up to two years of life out of a UF membrane, before replacement is necessary.
Ultrafiltration systems have gained popularity over the stable water quality it produces, regardless of the water source. It also features a compact physical footprint, with capabilities of removing most viruses and organic molecules. UF does not require the use of chemicals either, except when cleaning membranes.

Characteristics of a UF Membrane

Regular maintenance is the top way to prevent fouling of a nanofiltration membrane, due to scaling, solids, and other microbiological agents, including algae, and microbes. Ultrafiltration is categorized somewhere between nanofiltration, and microfiltration. Thanks to a pore size ranging between 0.1 to 0.01 microns, ultrafiltration membranes prevent 90% of a macromolecular solute from passing through. Ultrafiltration systems are most applicable to situations including:
  • Standalone systems
  • Water softening
  • Paper pulp mill effluent filtration
  • Food and beverage industries
  • Wastewater and industrial process water treatment and recycling

Benefits of Ultrafiltration

  • Doesn’t generate wastewater
  • Removes viruses and bacteria
  • Quick and easy installation
  • Operates at a lower pressure
  • Retains essential minerals
Ultrafiltration systems are considered to be rather eco-friendly. With a 90-95% recovery rate, uf can be used to treat wastewater, and prepare it for reuse. A home ultrafiltration water system often benefits the environment as well, by reducing the amount of discarded plastic water bottles overall.

Filtration Development

Modern membrane technology didn’t technically get it’s start until the 1990s, with ultrafiltration getting it’s start during the 1960s. This was following the heals of the discovery of the 1950s discovery of the RO membrane. While it was first described toward the end of the 19th century, ultrafiltration has come a long way. It also came after MIT’s discovery in the beginning of the 60s, when they discovered polyelectrolyte complex hydrogels.
When polymeric membrane chemistry and processing techniques were getting their start through the manufacturing of filtration membrane. UF was made more efficient through the discovery of these new materials and manufacturing methods. Overall, this poised UF as a competitive process for efficient water treatment solutions. In fact, the global ultrafiltration membrane market grew to a size of $5.3 billion in 2019. Though recent events caused a little bit of a slump, the market is projecting a substantial recovery in 2021. Efficient advancements, as well as increasing water safety regulations, are expected to drive adoption upwards.
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Best Under-Sink Water Filtration System for Home

Water filters recently became prominent, especially over the last three or four years. Before now, American households do not consider an under-sink water
filtration system as an essential. Young people tend to buy packs of bottled water from the market, while the older people usually get water directly from faucets.
American citizens believe that their municipal tap water supply has been subjected to vigorous purification and sterilization procedures before it enters their homes.
However, this view is losing its support by the day, with so many scandals related to water safety being revealed. An example is the case of Flint water crisis, where the tap water source was found
to contain an amount of lead large enough to cause poisoning in small children in Michigan.
Although water has been well-treated before being sent out of the treatment plant, contaminants may find their ways into the water during transportation. Lead is one of
such contaminants; it is often found in old pipes where it can cause lead poisoning if accumulated over time.
Therefore, it’s highly likely that water coming out from your home faucet contains lead, arsenic, and a bunch of other contaminants that can cause health problems in the short and, more often,
in the long term. Fortunately, with the discovery and evolution of filtration technology, we are better equipped to minimize the potential risks of contaminated water. There are now several filter options in the market to
choose from. That said, the most suitable type of water filters that meet the household water needs, including drinking and cooking, are under-sink water filter.
This article provides a detailed guide on the best under-sink water filters you can consider for your home and why you should consider each.

Best Under Sink Water Filter Review

1. iSpring RCC7AK 6-Stage Drinking Water Filter System – Best For Value

If you want to get a pure water filtration experience directly from the faucet, and would like to spend a bit more for improved water quality, you can choose the iSpring 6-Stage RCC7AK Under Sink
Water Filter System. The 6-stage RO filtration process provides thoroughly filtered and completely purified drinking water, which is aresult of a 99% reduction of more than 1,000 harmful contaminants, including chlorine,
fluoride, arsenic, asbestos, calcium, and more.
Asides from removing the basic impurities in tap water, the added sixth stage alkaline filter restores the beneficial minerals to your water for balanced alkalinity, giving you an improved taste
and ensuring you do not miss out on the minerals that are important to your health.
The system comes with an exclusive faucet, which means it cannot be connected to your main faucet. But you need not to worry about changeable installation. Everyone can simply install the system,
even without prior plumbing experience. Perhaps, the slight downside is the 3.2-gallon pressurized tank and its large size, which means you will need to create a lot of space under your sink.

2. Home Master TMAFC-ERP Under Sink Water Filter – Best to Buy in 2021

This Home Master TMAFC-ERP Artesian under-sink water filter system is a top model in the filtration industry. Its efficient filtration, 1:1 low drain ratio, and long-lasting filters set the
standards for other filtration systems. The filter quality is backed by a made-in-US guarantee and NSF certificated components from Perfect Water Technologies, Inc.
A common talking point of RO water filters is the large amounts of waste water they produce, even more than the RO water. For a traditional RO water filter, the drain ratio can sometimes get
as high as 5:1, which means that it produces 1 cup of RO water for every 5 cups of waste water. However, the innovative point of this Home Master TMAFC-ERP is its powerful permeate pump, which greatly improves system
efficiency. It saves up to 80% of waste water, reducing the drain ratio to 1:1 – this is probably the lowest you can get among reverse osmosis systems. This pump uses energy from the rejected water, and thus doesn’t
even require electricity to work.
There are three inbuilt filters in the system – the spun poly sediment filter, the catalytic carbon filter, and the coconut shell granular activated carbon water filter. The efficient
filters bundle, alongside the RO membrane, reduces up to 99% of dissolved solids, chemicals, heavy metals, and more.
Another special feature of this system is the catalytic carbon filtration media in the pre-filter. This material is especially effective in removing chloramine, a chemical used widely
as a disinfectant in the US. The Artesian remineralization also adds healthy minerals to the filtered water, especially calcium and magnesium, making it slightly more alkaline. This will show in your water TDS
reading, so don’t be surprised if the number is slightly high!
The whole system is composed of an RO membrane, pre-filters to protect the RO membrane, a post-filter, remineralizer, and a water storage tank. All the required components for
installation comes with the system out of the box, including a drain saddle, fittings, tubing, and an adapter. It also includes a faucet; therefore, you can have purified water from a separate tap.
The system provides you with everything you need for pure alkaline water from your own kitchen. In traditional RO systems, the filter housing can be reused with a replacement filter,
posing risks of re-contamination. The Home Master TMAFC-ERP makes its filter and housing integrated into one single unit with the modular filter design. This makes it slightly more expensive, but better
hygienically and less susceptible to re-conatmination.

3. Waterdrop G3 Tankless Reverse Osmosis – Best Under-Sink Filter for Drinking Water

The Waterdrop G3 reverse osmosis system delivers fresh ad pure RO water through a 7-stage filtration process. The sleek compact layout, smart indicating system, and a smart faucet all makes
it a go-to water filtration system, in addition to its efficient filtration process.
Three outstanding features differentiates the Waterdrop undersink RO system from the competing RO systems.
First, unlike the traditional under-sink reverse osmosis water filter systems that rely on a storage tank to pump water out, the Waterdrop purifies water delivers instant water the moment you turn
on the faucet, even without a water storage tank. This helps avoid secondary contamination of the filtered water, often caused by growth of bacteria and viruses in the tank.
Second, the system can produce up to 400 GPD (gallons per day) of purified water, while decreasing the drain ratio to 1:1, thanks to its in-built pump.
Third, the smart faucet has a LED ring on its stem, which will change into different color to indicate the status of the filtration system. When in use, the LED ring on the faucet shows various
colors to show you the status of the filtration system. Likewise, the frontal LCD panel on the filtration system shows both the filter status and the TDS (total dissolved solids) level of the filtered water in real time.
Other RO systems without TDS panels require a third-party TDS meter to check the water condition.
Since the Waterdrop G3 occupies less space thanks to its compact design, and delivers even more filtered water, it should be near the top of your list!

4. APEC Top Tier Alkaline Mineral pH+ 6-Stage – Best for Alkaline Water

If you want an under-sink RO system that removes harmful substances but keeps the beneficial minerals in the filtered water, the APEC Top Tier Supreme
Alkaline Mineral pH+ is the best for you.
The APEC offers five stages of water purification, similar to most high quality RO systems out there. The first filter is made of polypropylene, which removes large particles,
rust, and dust from the water, thus protecting the membrane. Then the water flows through two carbon block filters, reducing 99% of chlorine, odor, and bad taste.
The outstanding feature of the system is its High Rejection TFC RO membrane, which further removes any contaminants in the water, including arsenic, lead, chromium, radium, fluoride,
bacteria, and viruses. Finally, the filtered water passes through the post coconut shell activated carbon filter to remove the odor it picked up in the tank.
The water becomes pure and safe to drink after leaving the post filter. But the alkalization stage adds beneficial minerals, such as calcium to the water to further improve its taste.

5. CuZn UC-200 Under Counter Water Filter – Best non RO Filter

CuZn UC-200 Under Counter Water Filter is a complete water filtration system that fits your kitchen sink perfectly. It only filters out the harmful impurities; it retains the beneficial minerals,
which the body requires to stay healthy.
The filter offers a three-stage filtration process, which efficiently removes chlorine, heavy metals, sediments, and more. You can enjoy healthy, pure and tasty drinking water at all times.
If your source water is coming from the well, you need to make sure you have a pre-purified water source. The system is best suited for municipal water.
The filter has an ultra-long life of up to five years or 50,000 gallons of water, whichever comes first. Due to its integrated design, it only takes five minutes to install the filter.
The system also comes with an all-in-one components pack, which included all the necessary accessories to get the system working.


1. How often should I change my under-sink filter?

This entirely depends on the filtering system you choose. Many systems are rated to handle a certain number of gallons before needing to be changed. This information is provided by each manufacturer
and is something you should investigate before choosing an under-sink filter.

2. How long do undersink water filters last?

If you are keeping up with the filter changing routinely, the system will last for many years. If you forget to swap out your filters when they expire, you run the risk of contaminant build-up
that can hurt your water filtering system.

3. Can under sink water filters remove chemicals from water?

You bet they can! Each filtering system is equipped with the right filters to remove different contaminants from your water. Make sure you find the one that works best for your water supply!

4. Do under-sink filters waste water?

Yes and no. Standard and conventional filters do not waste any water because they are directly connected to the waterline. RO systems will require the presence of excess water, because they clean
the water via the reverse osmosis filter. Some RO filter systems will produce less wastewater than others.


In conclusion, an under-sink water filter system offers numerous benefits to you and your entire household. Compared to a whole house water filtration system, it is cheaper and more effective, and usually
requires less maintenance.
While deciding on which under sink filter to purchase for your home, make sure you factor-in the points raised in this purchase guide. You are most likely to make the right choice if you follow the detailed discussions above.
Thank you for viewing our guide. We are confident the best under sink water filter for you is hiding in here somewhere!
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