Introduction

The iSpring Ultrafiltration Water System CU-A4 is a high-capacity under-sink filtration system designed to provide clean, great-tasting water without the need for a storage tank. Launched in 2016, this product is manufactured by iSpring, a reputable brand in water filtration technology. Priced around $149, the CU-A4 features a four-stage filtration process that effectively removes up to 99% of contaminants while retaining essential minerals, making it an ideal choice for health-conscious consumers.

Featuring a four-stage filtration process, the CU-A4 incorporates a 0.1-micron UF membrane, a polypropylene sediment filter (PP), Active Carbon (AC), and Kinetic Degradation Fluxion (KDF) to provide crisp-tasting mineral water straight from your tap.

Specifications

Feed Water Pressure	20～80 psi*
Feed Water Temperature	40 -100ºF
Maximum Inlet Water TDS Value	≤1000 ppm
Clean Water Flow	0.56 GPM @ 45 psi
Filter Set Life Span	6～9 months @ 4 GPD

iSpring Ultrafiltration Water System CU-A4 Part List

Pre-assembled machine head:
Four filter housing caps on the bottom and two quick-fitting elbow fittings on both sides.
Four filter housings and four cartridges
1. First stage: Disposable PP filter (1st one on the right when facing the front panel)
2. Second stage: Disposable UF membrane filter in hollow fiber
3. Third stage: Disposable 85C granular activated carbon filter + KDF filter
4. Fourth stage: Disposable post-activated carbon filter (1st one on the left)
Drinking faucet and installation kit
Feed Water Adapter (AFW43)
Taps into the cold water supply angle stop valve with 1/2" and 3/8" adapter.
1/4 inch Tubing
Connects feed water adapter, filter unit, and drinking faucet.

Quick Tips

Inlet Water Valve in Different Sizes
Some homes may have either a 1/2 or 3/8 inch inlet water valve. The Feed Water Adapter (AFW43) includes a reversible adapter to match either size. For any other size, please get an adapter from your local plumbing store or contact us. If drilling is necessary, make sure that no power or water lines are in the way.

Use of Quick-Fitting

Viewing from the open end, quick-fitting starts with the Collet, Lock Clip (often in blue color), and Fitting Body.
To connect, cut tubing evenly, remove the Lock Clip, push the tubing 1/2 inch into the quick-fitting, and reinstall the Lock Clip. Pull on the tubing gently to make sure it is locked in.
To disconnect, remove the Lock Clip, and compress and hold down the Collet into the Fitting Body to eliminate the gap where the locking clip was occupying, and simultaneously pull the tubing out.

*NOTE* Watch our YouTube video ‘iSpring RO Quick Fitting’

HOW TO CONNECT

HOW TO DISCONNECT

Drill a Hole on Sink or Countertop

Watch YouTube video “how to drill a hole in granite countertop”
Choose one inch Diamond hole saw for granite and titanium drill bit for steel
Use a coolant to disperse heat. Choose water for granite and oil for steel
Use a 1-1/2" Suction Base Drilling Ring to hold coolant and prevent the drill bit from slipping on the counter
Start slowly. Be cautious with the power drill that might slip and damage the counter surface.
Set variable speed power drill at 100 – 200 RPM. Do NOT use hammer drill on natural stone, glass, and ceramic.
Hold drill bit vertically and swirl a little to apply pressure evenly in a circular motion.

Be patient and deliberate. It can take 20 - 40 minutes to drill through one inch.

Description

The 123filter Ultrafiltration Water System CU-A4 is engineered with a robust ultrafiltration membrane that captures contaminants as small as 0.01 microns. This ensures that the water you drink is free from harmful bacteria, viruses, and other microorganisms. The system also improves the taste and odor of your water by removing chlorine and other chemical impurities.

The CU-A4 features a sleek and compact design, making it perfect for under-sink installation without taking up too much space. The system comes with all necessary fittings and installation tools, ensuring a hassle-free setup process.

Installation

Note: Use the bushing (adapter) that goes with the AFW to fit the ½” NPT or ⅜” COMP threads on your sink's Cold Water Pipe.

Installation Steps

CAUTION: Improperly installed systems could result in water damage due to leaks or flooding. Proper installation of this system requires familiarity with standard sink plumbing and proper use of common hand and power tools. If you are not familiar with standard sink plumbing and proper use of common hand and power tools or have any difficulty with installing this system, please consult a licensed professional, such as a contractor or plumber.\

Preparation
- Location: This water filter can be installed anywhere with a proper cold water supply, such as under the kitchen sink, behind the refrigerator, next to your aquarium, inside the RV, etc.
- Tools needed:
  1. 3/8 inch and 1/4 inch wrenches or adjustable wrench
  2. Phillips and flathead screwdrivers
  3. Scissors or utility knife
  4. A bucket and towel to catch water drips
  5. Variable speed power drill with 1-inch steel or marble hole saw bit if a hole on the counter is to be drilled
Steps for installing under the kitchen sink (other locations may vary)
1. Installing the Feed Water Adapter
  1. Turn off your Inlet Water Valve (COLD) and open the kitchen faucet to release water pressure.
  2. With a towel or bucket underneath, disconnect the Faucet water hose from Inlet Water Valve using the 3/8 inch wrench and install the Feed Water Adapter (AFW) between them. Make sure the rubber washers are still in place. It is usually not necessary to use Teflon tape here. Hand tighten the hex nut and use the wrench for the final 1/4 - 1/2 turn. Do not overtighten.
  3. Install the 1/4 inch WHITE tubing on the Feed Water Adapter using the 1/4 inch wrench. Hand tightens it, then tightens up half to one turn using the wrench. If you received the feed water adapter with quick fitting, insert the tubing 1/2 inch deep into the fitting. It will lock automatically.
2. Installing the drinking faucet
  1. If your kitchen sink does not have a spare 1” hole, you will need to drill one. (Refer to Quick Tips for Drilling a Hole in Sink or Counter-top). Wipe clean, and dry the area.
  2. If there is a blue protection film on the Front Plate, remove it. Slip the front plate with a black rubber washer onto the faucet stem. Insert the faucet stem into the hole on the counter. Optionally, plumber glue or sealer could be used.
  3. Under the sink, slip on the Back Plate and tighten the Hex Nut.
    NOTE: 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.
3. Installing the unit and filter cartridges
  1. Match the stage labels and twist filter cartridges clockwise into the machine head in order. 3.2 On the cabinet wall, mark the two holes of the bracket and install two #8 x 1” round head screws to hang the unit.
4. Installing the tubing (check Quick Tips for using Quick-fitting)
  1. Connect the blue tubing with AFW, red tubing with 1st stage, white tubing with 4th stage.
  2. Check water route: cold water valve → blue tubing → drinking faucet valve → red tubing → 1,2,3,4 stages → white tubing → drinking faucet.
5. System startup
  1. With a towel or bucket underneath, slowly turn on the Cold Water Valve, feel the vibration and noise of the water flow. If your water pressure is high, DO NOT turn the Inlet Water Valve all the way up, but sparingly to a level position.
  2. If it leaks, check if the tubing is fully inserted into quick-fittings and that the nuts and
    cartridges are properly tightened.
  3. Turn on the Drinking Faucet. Water should start flowing. Let it run for 5 - 15 minutes or until carbon particles are flushed out and water turns clear. The water filter is now ready for use. Write down the current date on cartridge for future reference. The cartridge set has a life span of about 6 – 9 months depending on water quality and usage.
6. Filter Replacement
  1. Turn off the inlet water ball valve (COLD) and open the kitchen and drinking faucets to release pressure.
  2. With a towel or bucket underneath, twist the filter cartridge wrench counterclockwise to remove and immediately put the replacement back on. Work in the order from the 1st stage to the 4th stage, which is from right to left when facing the front label of the machine head.

Setup Guide

To set up the 123filter Ultrafiltration Water System CU-A4,

Start by turning off the cold water supply to your kitchen sink.
Next, disconnect the existing water supply line from the cold water valve and attach the provided adapter to the valve. Connect the inlet hose to the adapter and secure it to the system.
Mount the system under the sink using the provided mounting clips.
Connect the outlet hose to the faucet and ensure all connections are secure.
Turn on the cold water supply and check for leaks.
Finally, flush the system according to the manufacturer's instructions to ensure optimal performance.

iSpring Ultrafiltration Water System CU-A4 Troubleshooting

Symptom	Reason	Resolution
No clean water from the faucet	No water or water pressure < 20 psi Incorrect tubing connections Drinking faucet is off	Check water source Check the tubing connections Check the faucet
Slow water flow	Water pressure lower than 20 psi Filter cartridges are due for replacement 1^st stage is clogged by sediments	Open kitchen faucet to check cold water pressure Check the installation date and replacement schedule A whole-house sediment filter is needed to protect water appliances
No water from the fridge	Using the included faucet with an ice maker kit to connect to the fridge	Get iSpring ICEK fridge connector to connect your ice maker to water filter

Notes

Before you leave home or stop using the water filter for a period of time, turn off the cold water valve, AFW valve (cross position), and turn on the drinking faucet to make sure no there’s no remaining pressure.
Should any leak and damage to the parts occur, immediately turn off the AFW valve and contact us for assistance. (678-261-7611, support@123filter.com)

Pros & Cons

Pros

High Efficiency: Removes up to 99.99% of contaminants
Ease of Installation: Compact design with easy-to-follow installation instructions
Long Filter Life: Up to 12 months or 1,000 gallons before replacement
Improved Taste and Odor: Removes chlorine and other chemical impurities
Affordable: Competitive pricing compared to other ultrafiltration systems

Cons

Limited Flow Rate: May not be suitable for large households or high-demand situations
Filter Replacement Cost: Replacement filters may be more expensive than other types of filters
Requires under-sink space for installation

Customer Reviews

Customers have praised the 123filter Ultrafiltration Water System CU-A4 for its effectiveness in improving water taste and quality. Many have noted the ease of installation and the system's quiet operation. However, some users have reported issues with the flow rate being lower than expected.

Common Complaint

Is the cost of replacement filters, which some users find to be on the higher side. Despite this, overall customer satisfaction remains high due to the system's reliability and performance.

Warranty

This Limited Warranty extends to the original purchaser of the system only. This warranty covers all Manufacturer-supplied items only that prove to be defective in material, workmanship or factory preparation. This warranty covers parts only; all labor is excluded from this warranty, including, but not limited to, services related to the removal, replacement, installation, adjustment, maintenance and/or repair of the unit or its components items. excludes all non-Manufacturer labor required for any servicing of the unit, including, but not limited to, servicing related to installation, adjustment, maintenance and repair of the unit. This warranty applies only for the first full calendar year from date of purchase.

Warranty Registration

To register your product for the warranty, visit our website at https://123filter.com and go to the “Warranty” tab. We provide a 30-day money-back guarantee, a 1-year manufacturer warranty, and lifetime tech support for all of our products. However, we do not have the order information from websites other than 123Filter.com (Amazon, Home Depot, etc.), so please be sure to fill in that information upon registration of your system.

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