iSpring CU-A4 4-Stage Compact, High Efficiency Under Sink / Inline Drinking Water Filter System for Sink, Refrigerator and RV - Removes Bacteria, Giardia, Lead, Arsenic and much more

  • Superior 4-stage multipurpose water filtration system for safer, healthier, better-tasting water. The unique 4-stage design, which includes both Ultrafiltration and KDF/GAC stages provides the most effective water filtration in its class.
  • The 0.1 micron Ultra Filtration (UF) stage removes up to 99% of most problematic pollutants such as chlorine and chlorine treatment by-products, bacteria, giardia, lead, arsenic, and much more, while retaining healthy minerals.
  • Simple, compact and flexible, the CU-A4 provides highly effective water filtration for any number of clean-water needs - at the sink, in the refrigerator, for coffee makers and more. With no storage water tank and no waste water, the CU-A4 is perfect even for RVs.
  • All filters, tubing and other water-contacting parts are manufactured to comply strictly with FDA and NSF/ANSI standards for safety and water quality. Simple to install and simple to maintain, CU-A4 Easy-Twist Cartridges simply twist on and off.
  • iSpring supports all of its product with the best support in the industry. In addition to our 1-year limited warranty, we offer lifetime technical support provided by our dedicated support team based in in Alpharetta, GA and available at (678) 261-7611.
  • $169.99
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    • The CU-A4 effectively removes most problematic contaminants while maintaining a natural alkaline balance and great taste.

    • Designed and crafted in USA, iSpring is America's favorite brand of water filtration systems. All of our systems go through rigorous testing for air leaks, pressure and cycle resistance to adhere to our own demanding quality and high-performance standards. You are assured of many years of safe, trouble-free, low maintenance peace of mind.

    How It Works

    The CU-A4 is a multi-layered filter system that provides optimal protection against a wide range of contaminants while retaining healthy minerals. The system consists of 4 stages, each one designed to progressively remove contaminants and improve water quality and taste:

    Stage One: A Polypropylene (PP) sediment filter (5 microns) removes larger particles like rust, sand and dirt

    Stage Two: The UF stage holds the Ultrafiltration (UF) hollow fiber membrane. Capable of removing emerging contaminants like waterborne bacteria and waterborne protozoan parasites. These emerging contaminants can be pharmaceuticals or chemicals not yet regulated by the EPA.

    Stage Three: The third stage is a hybrid Kinetic Degradation Fluxion (KDF) Media and activated charcoal (GAC) filter. The KDF media sets the CU-A4 apart from other systems by providing much better control of particularly problematic contaminants including bacteria, algae, fungi, chlorine, pesticides, hydrogen sulfide, iron, lead, nickel, chromium, cadmium, calcium, aluminum, mercury, arsenic, and other organic compounds.

    Stage Four: The last fine activated carbon (GAC) filter provides final polishing before the purified water is delivered to the faucet, removing any possible residual chlorine, tastes or odors.

    Highlight Features

      • Easy Installation And Maintenance
        The CU-A4 is designed to be simple to install and simple to maintain. Push to connect fittings and color-coded tubing simplify the installation process. iSpring Twist On / Twist Off filter cartridges make changing filters a snap.

      • Ultra Filtration (UF) Filter
        The Ultra Filtration (UF) stage contains hollow fiber membrane technology with a pore size of just 0.1 micron, surpassing the performance of both carbon block and “portable mini” water filters.

    • KDF + GAC
      The CU-A4 is the only filter in its class to offer Kinetic Degradation Fluxion (KDF) Media which adds an important additional layer of protection to control microorganisms and metals.

    • Space & Water Saving
      Simple, compact and flexible, the CU-A4 provides highly effective water filtration for any number of clean-water needs - at the sink, in the refrigerator, for coffee makers and more. With no storage water tank and no waste water, the CU-A4 is perfect even for RVs.

    Product Description

    Simpler and more compact than Reverse Osmosis systems, the CU-A4 is an excellent choice for most general water filtration applications. The advanced 4-stage design of the CU-A4, featuring a unique combination of Activated Carbon, Ultra Filtration and KDF filters, virtually eliminates a wide variety of unhealthy contaminants, including bacteria, algae, fungi, giardia, lead, arsenic, iron, nickel, chromium, cadmium, calcium, aluminum, mercury, chlorine and chlorine treatment by-products, pesticides, hydrogen sulfide and other organic compounds. You experience safer, healthier and better-tasting water, without the hassle, expense and negative environmental impact of bottled water.

    The CU-A4 is flexible, quiet and durable. It has no moving parts and is very easy to maintain – only requiring occasional filter replacement. iSpring’s high-capacity, high-performance filters last up to twice as long as other filters and provide maximum water flow – a difference you’ll notice when you turn on the faucet. The iSpring “Twist on / Twist off” filter design means changing filters couldn’t be easier.

    A lead-free faucet with beautiful finish, included with the system, is usually mounted on the counter as the primary source of drinking water, but with a wide range of optional parts and accessories, the CU-A4 easily adapts to fit nearly any refrigerator or ice maker connection*. Contact iSpring directly and speak with a product specialist, to make sure you get the right filter options for your needs.

    We know that many customers prefer do-it-yourself installation, so the CU-A4 has been designed from the ground up to be easy for most users to install themselves, using readily available tools. Our push-to-connect fittings and color-coded tubing simplify the installation process and minimize the possibility of leaks. A well-organized instruction manual guides you step-by-step through the entire installation and testing process.

    If you do run into an issue, or get stuck, our technical support team is ready to assist you, Monday thru Friday between the hours of 9am to 5pm Eastern time. The whole system is backed by a 1-year money-back guarantee, a 1-year manufacturer warranty and iSpring's unique lifetime technical support provided right here in the USA in Alpharetta Georgia.

    So, if you have a need to reduce overall dissolved solids in the water (reduce TDS) or to remove heavy concentrations of harmful metals like lead or copper, then an Reverse Osmosis system like the iSpring RCC7 is recommended. But for all-around high-performance water filtration, or where space is at a premium, the CU-A4 is the best, most economical and flexible choice for clean, fresh, great-tasting water instantly.


    If you plan to use the CU-A4 as an inline filter (meaning using it without the included air-gap faucet), your incoming water pressure needs to be 40 PSI or below. If it is above that, a 40 PSI pressure regulator (APR40) should be installed on the input line to keep the pressure on the system at 40 PSI or below.

    Please contact us if you plan to “tee off” the pure water line and connect it to your fridge, as you would need a regular RO faucet along with a pressure regulator.
    • Availability: In Stock
    • Model: CU-A4
    • Manufacturer: iSpring

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