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iSpring CU-A4 0.01μm Ultra-Filtration Under Sink Water Filter System, Tankless 4-Stage High Capacity, Remove 99.99% Contaminants, Quick Filter Change with Brushed Nickel Faucet, White

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$153.89

$ 69 .99 $69.99

In Stock

1.Size:3.2 Gallons


About this item

  • SUPERIOR PERFORMANCE: The advance 4-stage design, which includes both Ultrafiltration and KDF/GAC stages, removes up to 99% of chlorine and chlorine treatment by-products, lead, and much more, while retaining minerals. Noted: This system is NOT a Reverse Osmosis water filtration system and does NOT lower TDS.
  • 4-Stage ULTRAFILTRATION SYSTEM: PP Sediment Filter (5 microns) removes larger particles like rust, sand, dirt. Ultrafiltration membrane contains hollow fiber membrane technology with a pore size of just 0.01 microns. KDF and GAC Filter provides much better control of particularly problematic contaminants including chloramine, hydrogen sulfide, heavy metals, and other compounds. Fine Activated Carbon Filter provides final polishing.
  • SIMPLE AND FLEXIBLE: NO WASTE WATER and No storage water tank required. 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.
  • FEATURES: Come with premium brushed nickel finish drinking water faucet. All filters, tubing and other water-contacting parts are manufactured to comply strictly with NSF/ANSI standards for safety and water quality.
  • EASY-TO-INSTALL AND REPLACE FILTER: Push to connect fittings for simplify setup. Filter replacement are designed for ease. No need to disconnect hoses or water lines. Just Twist On / Twist Off filter cartridges make changing filters a snap. Filter life: 6 -12 months, depending on your source water and usage.



Product Description

under sink ultrafiltration water filter system

Protect your home, health, and appliances by filtering your water with the CU-A4 Ultrafiltration Water System.

ultrafiltration water filter

4-Stage Efficient Filtration

The CU-A4 effectively removes the most problematic contaminants while maintaining a natural alkaline balance and great taste. With advanced compound filters, it effectively reduces silt, rust, large particles, heavy metals, micron substances, matter, chlorine, taste, and odor, thus improving water taste for direct drinking, coffee, or beverages. It retains natural minerals.

0.01 micron water filter

Easy Installation and Maintenance

The CU-A4 is designed to be simple to install and 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. A drinking faucet is also included in the package.

4 stage under sink water filter

Premium Complex Filter Superior Over Others

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 heavy metals. The Ultra Filtration (UF) stage contains hollow fiber membrane technology with a pore size of just 0.01 micron, surpassing the performance of both carbon block and 'portable mini' water filters.

kitchen water filter system under sink


4-Stage Filter Replacement

tankless under sink water filter
Why iSpring?

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 trouble-free, low-maintenance peace of mind.

Why CU-A4 Ultrafiltration Water Filter System?

The Advanced 4-Stage Under Sink Ultra-Filtration Water Filter System reduces major most problematic contaminants from your water supply while maintaining a natural alkaline balance & great taste, and supplies clean water for drinking, showering, cooking, and other home uses.

  • PP Sediment Filter (5 microns) removes larger particles like rust, sand, dirt.
  • 0.01 micron Ultra Filtration membrane can effectively removes all colloidal particles (0.01 to 1.0 micron) and some of the largest dissolved contaminants from water.
  • KDF and GAC Filter provides much better control of particularly problematic contaminants, such as chloramine, hydrogen sulfide, heavy metals, Volatile Chemicals (VOC), chlorine and more.
  • Post Activated Carbon (0.01-Micron) can further absorb the peculiar smell of the water, increase the oxygen content of the purified water, and mainly improve the taste of the water.

water filter under sink for drinking water

Not For TDS Removal

Please note: This under sink water filtration system DOES NOT lower TDS, instead it will keep minerals in your water. If you are interested in a filter that eliminates TDS, please consider under sink Reverse Osmosis (RO) system RCC7.

drinking water filter system

Leak-Free System

Push-to-connect fittings and colorful coordinated tubings simplify the installation process and prevent leaking. The o-rings are made of premium materials to make sure that the filters will be properly sealed without any leakage.

ispring water filter

Save More Space

The iSpring CU-A4 Under Sink Water Filtration System can be mounted easily under sink, leaving you more space for storage and letting you filter water directly. The slim & compact design is ideal for homes, apartments, offices, and RVs as it can be easily installed and allows you to pack more belongings.

ultrafiltration water filter system

Cost-Effective System

Our ultrafiltration system offers a cost-effective and convenient way to enjoy clean, filtered water in the comfort of your home. Unlike other filtration systems, our long-lasting filters require no electricity, making it a sustainable and affordable option for any household. you can save a significant amount of money on expensive bottled water and water delivery services.


David B.
2025-08-28 11:16:07
Got tired of the water dispenser in the frig, which would drip onto the floor from constant use (family of 4). Got a new frig without one and added this filter to a new sink and faucet which is so much more practical and convenient, especially making coffee each morning. I bought this based on the reviews and 0.01μm as opposed to 0.5 μm by other leading brands. I also wanted a Tankless system that required no power but provided great filtering. 4-Stage High Capacity that removes 99.99% Contaminants is impressive - but time will tell (installed a week ago). The Brushed Nickel Faucet is very nice and dispenses at a fast rate, it also matches my new faucet :). No leaks but I did place a mud tray under it and will add an H2O sensor - a good idea from another review - as I was not liking the sensor that came with the kit that added complexity to the hose hookup. Installation was easy - watch their video. Emailed customer service for the warranty and they were great (thanks Francis!). So far I'm very pleased. Water tastes clean / no chlorine or otherwise. Replacing the cartridges should be easy - don't forget about that when you install this filter - keep it simple and accessible.
Customer
2025-07-21 14:42:13
The tank works great! It comes pressurized already and has a head gasket that you can connect the valve with a snap. Super easy to install and setup. Definitely worth the price and quality
Jimbo
2025-05-03 20:04:27
Update: As per my review below, I had some trouble installing due to instructions that were not really clear or suited to this particular product, which Ispring says is brand new. Since then they actually tracked me down and cared about what I had to say. According to them they are rewriting the instructions, not shipping with the funny dust caps, and considering additional parts to make the installation go smoother. I was impressed because in this day and age few companies actually seem to care about what their customers really think. I have come to the conclusion that this company does. And the filter system is now working fine, so don't hesitate to buy. I'm leaving my review below in case it takes a while to update the instructions. It might shave a few hours off someones install time. Changed to 5 stars. If you have any problems they will definitely help, and that is a really good thing.================================================================Just finished the installation. I'm a pretty handy monkey, but the installation took about 5 hours of my time (including 3 trips to the home improvement store and a some-what helpful phone call to ispring).First-off the manual is misleading and clearly written for another product or previous version of this product (or maybe a new-fangled sausage making machine). The parts of the manual that do apply to this product, like how to connect the little push-on connectors, suffer from an excess of brevity and lack of detail and conciseness.In an attempt to be helpful to future purchasers of this product, at least until ispring updates these kits and instructions, here's what I learned:First tip: the faucet included in my box does not require a 1/2 inch hole, as the instructions state, but a one inch hole. Actually one inch is too tight, make sure you have a 1 1/8 inch hole saw attachment for your drill, and make it a good bi-metal one if you need to cut through a stainless steel sink. Home depot sells rigid brand bits that suit this purpose. It will run you about $15 unless you already have a rigid brand bit shaft (or equivalent).Second tip: the faucet that came with my filter has three colored plastic hoses already permanently attached. Red, white and blue (I dig the patriotism). Unfortunately which gets attached where is not mentioned anywhere in the manual. In the manual it says to screw the water hose to the bottom of the faucet. Clearly referring to a different type of faucet. Also if the three hoses were just a little longer you would probably not need to bother adding extension hose (an extra leak risk). More on extension hoses later. The colors are mentioned in the Amazon description, way at the bottom, but it bears repeating. "Connect the BLUE tubing of 3-color tubings on the faucet to cold water line, RED to the 1st stage on the right, WHITE to the 3rd stage on the left." Note: This is #ssbackward if you are from an English speaking country ... just saying.Third tip: The filter box itself has funny little horn or funnel shaped things on the ends of the inlet (left) and output (right) angle connectors. These are not mentioned at all in the manual. You can not push the hoses on with these in place (you can try as I did ... if you get excited by frustration) because these are some weird sort of dust plugs. You must pull up with your fingernail on the very outer ring of the connector (pushing it on a spring ever so slightly towards the more bulbous part) then with other hand pull the horn thing out. You can discard these, or I found they make nice hats for very small garden gnomes.Basically you can connect the red and white hoses now by pushing them with force into the connector until they snap. Pull back a little to make sure it is connected. If you need to cut extension hose cut it straight, and use the supplied double-sided connectors. I recommend you push the little blue horseshoe shaped clips (supplied) between that outer part of the connector and the more bulbous part. These (I think?) are to make sure the connectors can't shoot apart from water pressure. No mention in manual about these. You can leave them off, as I did at first, if the under side of your sink needs a good spraying out.Fourth tip: In order to connect the blue hose to the cold water line you need to first install some parts. My sink had a 3/8 inch stainless steel hose with female compression fitting attached to a male 3/8 compression fitting shutoff valve coming out of the wall. Pretty typical I would assume. The kit comes with a 1/2 inch plumbing style thread, male to female connector, with a hole to thread the valve the blue hose goes onto, in the middle. A way to tap into your cold water line, would be eazy peezy if it was threaded for 3/8 compression fittings, but it's half inch and has coarser plumbing style threads.So off to the Home Depot you go. Don't forget another roll of Teflon tape to add to your Teflon tape collection while you are there. Actually the folks at the Home Depot weren't that helpful (surprised?), but the small local hardware store in my old town was. You will need, as it turns out (if your sink is like mine) a 1/2 inch plumbing style male to 3/8 inch compression male adapter to connect your current hose leading to your cold faucet to this new part (btw thread the little supplied valve the kit came with into this part with a little teflon tape first so you can get it good and tight before you are lying on your back under the sink). Then on the other end you will need another short stainless hose (only way I can find to do this with available parts ... why it took three trips) 1/2 inch plumbing female, which attaches to other end of this new part, 3/8 compression female which connects to the part your faucet hose used to be connected to. These parts should run less than $15.Tip five : To connect the blue hose to the metal valve from the previous section you need to put it against the nipple, screw off the nut collar and slide it down the hose temporarily, then push it on the nipple all the way, and man it's a tight little bugger (I sprayed the nipple with a little Pam cooking spray, hey it was in the kitchen), then put that nut collar back on and tighten it down real tight with a half inch wrench.Why these filters don't come with a 3/8 inch compression fittings on each side of the filter box, so you can just screw your standard hoses on that you can get from any hardware store, is beyond me. There must be a reason. Maybe these filters are designed by the same folks who design those charming "blister packs" that you need a chainsaw to open?When I tested the water it was cloudy and tasted a little funny, it got better after I ran the tap for a while. Now it tastes pretty darn good. Even my cat likes it. Hopefully it will not develop leaks.
Computer Dr.
2025-03-25 11:50:46
Edit 2: It's November 2023, 5 years later, still working A-OK. The espresso habit acquired last year now also demands tasty water, lol.Edit: 2.5 years and three sets of filters later, still no issues to report. I made a couple tweaks below. Read #1 - very important!This is a great filter for anyone who wants to leave the good minerals in your water and filter everything else out. The only better filtration is reverse osmosis, but it needs its own separate storage tank so the water is just room temperature, and it has a metallic taste and low water pressure = slow flow.After significant research we decided on this filter for all the reasons above. This fit the bill perfectly with a healthy four filtration stages, great flow and no RO! I had it running in a half an hour with simple inline connections to the 'fridge water line and it eliminated the pesticides and city water taste instantly.Important Notes:#1) This one tip might save you from expensive plumbing repairs down the line and is something you need to know before you install this unit. TEST YOUR WATER PRESSURE! This filter needs to be run at under 80 PSI. There are various $10 simple screw-on testers like the Watts IWTG that take seconds to use. I attached the tester to our backyard hose hook-up and discovered we were at 80 PSI. We then tested my in-laws' house and they were at 92 PSI. No big deal right? Well residental water pressure should be under 60 PSI, ideally 50 to prevent water hammer (banging pipes) and damage to copper plumbing pipes over time! After installing a water pressure regulator on the main water line in the basement ($100 from local hardware store and a couple hours' work) we immediately noticed the pipes wouldn't bang when we flushed a toilet, or when the clothes washer ran. Plus, the filter was now right in its sweet spot of 40-80 PSI. If your water pressure is over 60 PSI, at the very least add the iSpring APR40 to your purchase to reduce the pressure to this filter to 40 PSI and help protect it from damage.#2) As others have mentioned there is a slight oily sheen in the water upon first installation. The oil is there to help seal the cartridges. Simply run 15 gallons of water through the filter to purge it all out, really not a big deal, see images 2-3. Residue and cloudiness are common to nearly ALL water filters upon first installation and the 1-star complaints are indicative of inexperienced DIYers.#3) The included push-to-fit 1/4" water line couplers work on both Copper and PEX/plastic tubing as they are both relatively soft materials with the same outer diameterWater tastes like bottled now and we're extremely satisfied, plus no more pesticides. If I have any problems, you know where I'll be posting them!
Ryan
2025-02-15 18:02:53
I waited a while to write this review as I wanted to see how this held up for a month. I can say this has worked perfectly, looks classy (not cheap), and the water has since a nice clean taste. I should have put this in years ago however I was always concerned that it would be too hard to do, or would leak or just from not knowing enough how these work.The install was literally under 20 minutes, so straight forward and the components, hoses etc are high quality. The hardest part was drilling a hole in the stainless steel sink, however I did not care much as the sink is old and we are renovating the kitchen fairly soon.Connecting the hoses was literally a snap, the unit fits under the sink no problem, and I made sure to leave the hoses longer so I can pull the unit out easily to change the filters.The faucet itself looks high end and the lever has a nice weighted feel to it, not cheap moving, more of a smooth range of motion. The only thing I wish was a little more solid was when I turn the faucet from side to side, say filling up the dog bowl on the counter, it is kind of flimsy, I wish this had the same feel as the water lever did.When I hooked everything up I had to let it run for a good 30 minutes to clear the filter sediment out, and for the first couple days when first used in the morning, there would be some sandy sediment. That was gone by the third day and crystal clear since then.I want to get the water tested and compare to this to see what is really filtered, that is my only question, you are taking the companies name that the filters work, and this is why you need to review and do some research.So far very happy and would buy again no problem!
Luis H.
2025-01-15 13:38:07
Tarde mucho en elegir y me decidí por estos filtros por su fácil instalación , fácil cambio de cartuchos después de 12 meses , y el precio muy recomendables . Debes dejar que fluya por 15 min antes de tomar agua cuando es la primera vez que se use los filtros. La empresa que los hace es de USA y tienen buenas reseñas en ese país eso da mucha tranquilidad ,que vienen de una empresa sólida.
Ivan Salazar
2024-12-29 18:14:26
El tanque llegó en perfectas condiciones. No tienes que comprar el adaptador porque ya lo incluye. Además es compatible con otras marcas de sistemas de filtrado de ósmosis.Me tomó 2 minutos instalarlo.Lo recomiendo ampliamente.
MP
2024-12-24 10:13:31
Less expensive than replacing the entire RO system. The old tank was defective and this one worked perfectly once the reservoir was filled. It has a good reserve of clean water. Much better than having the slow trickle at the speed of the Osmosis system. Now it's WOOSH and your container is full... let the system work at replacing the water before the next time you need some, without you standing there. No more holding the container forever as water dribbles in.
Bill Smith
2024-12-23 18:53:44
We never run out of drinking water. The original 2 litre tank was totally inadequate. I hooked this one and the old one together.However, I needed to order a part to enable the union.
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