Water Filtration Systems

Variety of water filtration systems and options

What are Water Filters?

Water filters are devices or systems designed to remove impurities, contaminants, and unwanted substances from water. Some filter methods work by passing water through a filtration medium, which can be made of materials like activated carbon or a combination of different filter media. Other systems use ultraviolet light to treat viruses and bacteria in water.

Water filters are commonly used in homes, restaurants, manufacturing facilities, and various other settings to improve the taste, odor, and overall quality of water. They can effectively remove particles, sediment, chlorine, heavy metals (such as lead), bacteria, viruses, pesticides, and other harmful substances, providing cleaner and safer water for consumption or other uses.

The Four Types of Water Filters

    1. Four common water filtration methods include UV sterilizers, reverse osmosis, activated carbon and sediment filtration.
    2. UV Disinfection: Ultraviolet (UV) light is used to destroy bacteria, viruses, and other microorganisms by disrupting their DNA, rendering them unable to reproduce.

    3. Reverse Osmosis (RO): RO systems use a semipermeable membrane to remove a wide range of contaminants, including dissolved solids, heavy metals, arsenic, fluoride, chlorine, pesticides and more.

    4. Activated Carbon Filtration: This method uses activated carbon to remove chlorine, volatile organic compounds (VOCs), and some chemicals from water, improving taste and odor.

    5. Sediment Filtration: Sediment filters remove larger particles, sand, rust, and debris, preventing them from reaching faucets or appliances.

What are the Best Water Filtration Systems?

There are a wide variety of treatment systems designed to improve the quality of your water. But which type of water filtration is best for your needs?

That depends on what's in your water (which contaminants are present), if you're on well water or city water, if you're looking to treat water for the whole house or simply wanting to improve your drinking water.

To figure out what system is right for you, we invite you to take our interactive quiz which will provide you with a personalized suggestion.

Point of Use vs. Point of Entry Water Filter Systems

There are many types of home water filtration systems available, but they can generally be divided into two categories: point of use (POU) and point of entry (POE) systems.

        1. Point of Use (POU) under-sink filter systems
        2. Point of Entry (POE) whole-house filter systems

Point of use (POU) systems include:

  • Under-sink Filters: These filters are installed under the sink and provide filtered water to a separate faucet.
  • Faucet Filters: These filters attach directly to your faucet and use a combination of activated carbon and other technologies to remove contaminants.
  • Countertop Filters: These are larger filtration systems that sit on your countertop and use a combination of filtration technologies to remove contaminants.

Point of Entry (POE) systems include:

  • UV Disinfection: This water treatment system uses ultraviolet light to kill bacteria and other microorganisms in your household water.
  • Whole House Filters: These filters are installed at the main water line where it enters your home and remove contaminants from all of the water that enters your home.
  • Water Softeners: These systems use a process called ion exchange to remove minerals like calcium and magnesium from your water, which can cause hard water. We currently do not carry water softeners.

Point of use, or POU, drinking water filters are used to remove impurities from water at the point that it is actually being used.

What is a Point of Use Water Filter System (POU)?

A POU (point of use) water filter system is a type of water treatment system that is designed to filter water at a single point of use, such as at a specific faucet or drinking water dispenser. These systems are typically installed where the water is used, such as under the sink, on the countertop, or attached to the faucet.

POU water filter systems are typically smaller and less expensive than POE (point of entry) systems, and they are designed to remove a variety of contaminants from the water, such as sediment, chlorine, lead, and other chemicals or impurities that can affect the taste, odor, and quality of the water.

There are several types of POU water filter systems, including pitcher filters, faucet filters, countertop filters, and under-sink filters. Each type of filter uses different technologies to remove contaminants from the water, such as activated carbon, reverse osmosis, or distillation. The type of filter you choose will depend on the specific contaminants in your water and your personal preferences.

Point of use systems or "POU" filters are generally installed at the kitchen sink for filtered drinking water. These single faucet filter systems may be either a Reverse Osmosis filter system or a UV water sterilizer. Some point of use systems can be installed on the countertop, but most customers prefer under sink installation. Under counter filtration systems are plumbed to the main cold water supply.

A wide variety of series filters are available to address a large number of contaminants in water.

Top-Selling POU Filter Systems

Single-Faucet VT1 UV System

The VIQUA VT1 UV system is perfect for low-flow applications like single faucets. With a flow rate of 1 GPM, the system is a highly-efficient water treatment solution. The compact size and stainless steel chamber makes for easy installation. The VT1 features a simple indicator light and is capable of operating at 100-240V, 50-60Hz. Treat your drinking water with the Viqua VT1 UV system.


Single faucet UV systems, such as the Viqua VT4 can treat water at a single faucet within a home or cabin. The VT4 can produce 3.5 gallons per minute of treated drinking water. The system's compact design allows for installation under the sink or at a water fountain.

What's a Point of Entry Water Filter System (POE)?

Point of entry or "POE" water filter systems are designed to treat water for the entire home and are commonly referred to as whole house systems.

A point-of-entry system is installed where the main water line enters the house, and generally has a flow rate of 5 to 20 gallons per minute.

Just as there are a wide range of water-related contaminants, there are a variety of water treatment methods available for point of entry applications, including Ultraviolet, Reverse Osmosis, and general water filtration.

Top-Selling POE Filter Systems


A whole-house Reverse Osmosis system might be the right solution when you have a high level of a specific contaminant that is most economically removed by reverse osmosis.

Before installing, consult with a local water treatment professional to determine if whole house reverse osmosis is the best solution.

Learn more about the Axeon BT-1500 whole-home 1500 gallon-per-day reverse osmosis water filter system.


Whole-home UV water treatment systems provide peace of mind. The D4 UV system can treat all of the water coming into your home by inactivating waterborne microbes such as cryptosporidium, giardia, E. coli, legionella, norovirus, and hepatitis A virus †. This protection is especially important for those on well water, but can be equally vital for households on city water. Learn more about UV water treatment or check out our UV Buyer's Guide.

Common Water Filter Products

Whole House Water Filter Systems

A whole-house water filter will connect to the main water supply line in your house. This way, all the water throughout your home will be filtered, including water used in washing machines, showers, dishwashers, and all faucets.

Whole-home UV systems are a popular option as they give peace of mind 24/7. UV systems can inactivate waterborn microbes.

Under Sink Water Filter Systems

Under-sink water filtration systems are designed to treat the water at one faucet. This may be a reverse osmosis drinking water system that captures contaminants such as mercury, asbestos, lead, pharmaceuticals, and chlorine. Or if you're on well water, you may want to install a single-faucet ultraviolet water purification system to protect against illness-causing bacteria and viruses.

Replacement Filters for Water Filtration Systems

At ESP Water, we offer high-quality replacement filters for dozens of filter brands, including Culligan, Axeon, Rainsoft, Aqua Flo, and many more. We've bundled together the filters you need into "replacement kits" to make the annual filter change process simple.

We also carry a variety of sediment filters, carbon filters, pH filters and more.

Replacement Parts for Water Filter Systems

You'll find hundreds of replacement parts on our site, including uv lamps and sleeves, faucets, tubing, tanks, lamps, filters, fittings, housings, wrenches, cold water line connectors, and more. Check out our reverse osmosis replacement parts and UV replacement parts. If you have any questions about the part you're looking to replace, feel free to contact us.


How does activated carbon filtration work?

Activated carbon filtration works through a process called adsorption. Activated carbon is a highly porous material with a large surface area that attracts and traps contaminants from water. When water passes through an activated carbon filter, the contaminants in the water are adsorbed onto the surface of the carbon. Learn more on our carbon filtration page.

Is reverse osmosis better than other filtration methods?

Reverse osmosis excels in removing a broad range of contaminants, but whether it's better than other methods depends on your specific needs. Under-sink RO systems are an efficient and cost-effective way to have filtered, great-tasting drinking water.

How effective is UV disinfection in killing bacteria and viruses?

UV disinfection is highly effective in killing bacteria and viruses. The UV light damages the DNA/RNA of microorganisms, rendering them unable to replicate and causing their destruction. It's a proven method for water treatment, providing a 99.99% or greater reduction in harmful pathogens without the use of chemicals.

How does sediment filtration improve water quality?

Sediment filtration improves water quality by removing visible particles like dirt, sand, rust, and debris. It prevents clogging in plumbing fixtures, protects downstream filters, enhances water clarity, and reduces sediment-related issues.

Which filtration method is most cost-effective in the long run?

The cost-effectiveness of a filtration method depends on various factors like initial investment, maintenance, and lifespan. While each method has its own considerations, ultraviolet water disinfection systems start at just over $300, don't require any chemicals, use very little energy, and annual UV lamp replacement is the only ongoing cost.

Answers To Your Most Common Questions

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