iSpring F9K NSF Certified 1-Year Reverse Osmosis Water Filter, Alkaline Remineralization Filters for 6-Stage RO Systems, Without RO Membrane

Super system at this price! We've bought it years ago. Of course, the filters fit. We installed the iSpring reverse osmosis set a few years back. It is well worth it's money by now. Water from regular interval filters tastes good to me, and I am sensitive when it comes to water's taste. Can't drink odd or off tastes without cringe. I like arrowhead though not in ecstasy about it, not ok from plastic bottles stored in hot weather except in emergencies. I like some mountain streams and some wood springs, am ok with occasional, light carbonation - though it won't improve the taste, just change and mask it. We also used different $15-30 test strips on occasion throughout the house and this water's our clean baseline. I hate chlorine taste and feel and do not want more iron or lead or PFAS than necessary, either. There's only so much antioxidants can do for us. So, despite the terrible fact that this system wastes 2x the amount of water you get from it (wish we could rig it so the excess watered our garden or plant) - this is totally worth it to me. I try to meditate when filling a bottle to put in the fridge for the day, it takes about 20 seconds. It's not so bad with just a glass, but it also isn't for the super easily annoyed. Our storage canister, which is slowly refilled with pre-filtered water after you tab out some, is great for two or three people to drink and cook. If you need a lot of water at a time, you might require a larger system. Think of the time saved hauling and trashing bottles, that gives ample patience and glee to the adults at least. Installation is a bit tedious but straightforward enough. And here's a secret superpower: iSpring's customer service is actually super friendly and helpful! After some years the system started dripping (to refill the reservoir) and just didn't stop unless we turned off water. Called CS and they helped us troubleshoot successfully. Yey! If you have no savy at all, get someone to install this for you and set a reminder to replace filter cartridges on schedule. Especially renters profit from the compact and relatively easy system, it takes some space but leaves enough of room under our double sink for two small trash bins and detergents. The shower's got a cheaper filter (which won't waste) and I would NOT drink that water. It's just barely ok on the skin. This water quality's actually impressive given the price of this system is in the low hundreds. Even disregarding eventual medical bills you prevent, you'll save that back financially by just stopping to shop bottled water. We get solid bottles and just refill, wash, refill for up to a year of reusable, high quality plastics or years on end with stainless. Health, economy, even ecology benefit (considering this set lasts us years now and we used to buy plastic bottles, made with a lot of damage to water) - We're very happy.

I have been running a 6-stage reverse osmosis system for a year, and while RO water is incredibly pure, it can often taste "flat" or become slightly acidic due to the removal of all minerals. I chose the iSpring F9K 1-year replacement pack specifically for the Alkaline Remineralization stage, as I wanted to restore the essential minerals and raise the pH to a more "natural" spring-water level. Filter Quality & NSF Certification • The Build: These aren't generic "knock-off" filters. You can feel the weight difference in the high-capacity sediment and carbon blocks. The fact that they are NSF/ANSI certified provides peace of mind regarding the safety of the materials used (no lead or BPA leaching). • Remineralization Stage (AK Filter): This is the star of the pack. It uses red mineral stones and calcite to add calcium, magnesium, and potassium back into the water. In my testing, it successfully raised the pH of my RO water from a slightly acidic 6.5 to a much more alkaline 8.2. • Carbon Block Efficiency: The 5-micron CTO carbon block is exceptionally dense. I noticed an immediate removal of the slight "chlorine" scent that had begun to creep into my system as the old filters reached the end of their life cycle. Installation & Fitment • Standard Sizing: These are standard 10-inch filters. They fit perfectly into my 10" housings with no "bypass" issues or rattling. • O-Ring Integrity: The seals on the sediment and carbon filters are high-quality rubber. I didn't experience any of the "crimping" or leaks that sometimes occur with lower-tier replacement packs. • Flushing Process: Every carbon filter requires flushing to remove "fines" (loose carbon dust). I ran the system for about 10 minutes, and the water cleared up significantly faster than with previous brands I’ve used, indicating a cleaner manufacturing process. Pros & Cons ✅ Pros: • Comprehensive 1-Year Supply: Includes all pre-filters and the specialized alkaline stage (minus the RO membrane, which usually lasts 2-3 years). • Superior Taste Profile: The remineralization stage gives the water a "crisp" mouthfeel that pure RO water lacks. • System Protection: The high-quality sediment filter does an excellent job of protecting the more expensive RO membrane from clogging. ❌ Cons: • No Membrane Included: As the listing clearly states, this doesn't include the RO membrane. Ensure you check your membrane's age before ordering just this pack. Final Verdict The iSpring F9K is the gold standard for maintaining a 6-stage system. It doesn't just "clean" the water; it "engineers" it for better health and taste. If you value consistent pH levels and want a certified filter that won't leak or bypass, this is a necessary investment for your home’s water quality. Helpful? If this breakdown of the pH levels and filter density helped you, please click the "Helpful" button below!

Works well with no issues. I really appreciate the included push-to-connect fittings, makes the installation much quicker.

I’ve owned my iSpring RCC7AK since 2020 with zero issues. Recently, after a routine filter change, the blue drain line to the AFR300 began leaking. After failing to fix it myself, I called tech support and spoke with John. Even though I explicitly reminded him that my unit was over 5 years old, John didn't hesitate: "It's fine. I'll order one AFR300 for you for free." He had me email my Amazon receipt, confirmed the order the next day, and a few days later, the replacement part arrived via USPS. I installed it, and the leak is gone. iSpring truly stands by their products, even years down the line. Having to drink tap water while the system was down reminded me just how terrible unfiltered water tastes. This system is worth every penny and is far cheaper than a water delivery service. Highly recommended!

We purchased our third iSpring RO system in October 2025 after having excellent experiences with the systems in our previous two homes. Last week, the clear Stage 1 housing on this unit developed a small leak caused by a hairline crack. We reached out to iSpring, and Sean responded almost immediately. He quickly arranged to send replacement parts along with a pressure regulator. As newcomers to Southwest Florida, we weren’t aware that many homes here experience relatively high municipal water pressure, which can contribute to issues like this. We really appreciate the outstanding customer service and the prompt resolution. It’s reassuring to know that iSpring stands behind its products, which is one of the reasons we will continue to choose iSpring.

I’ve been using this 1 year reverse osmosis filter set for a while and it does an excellent job and keeps the water nice in my 6-stage RO system. The NSF cert is reassuring for knowing the filter quality I can expect, and I have experienced clean clear good tasting water ever since I put these filters in! The alkaline remineralization really does put back some nice minerals and I’ve noticed the water is more tasty than the plain RO filtered water. The filters are well-made and fit perfectly into my system without leaking or any other problems. The only thing that I find sort of a pain is that it’s hard to tell which specific filter is which until you open up the individual plastic bags - some are very similar looking, and the outside packing is not necessarily clear concerning which bag has which filter. It would be much better if they each sealed bag had some clear printing on it of what type of filter is inside it, and the stage number it belongs to. Occasionally, I have to open one up just to make sure it’s the right filter, and that is a bit annoying at replacement time. Overall, each filter works like it should and lasts the whole year as advertised! Worth the price and it was easy to replace. It is compatible with my iSpring 6-stage.

I purchased this system in February 2018, I wanted to wait a while to see how it performed before writing a review. I have a background in water quality and am a bit of a water snob so I had very high expectations for quality and the water it produced. Installation was great, they include everything you need to install it on existing equipment. It attached to the cold water angle stop for your sink, they have a nice brass t fitting that will adapt to whatever you have under your sink either 3/8 or 1/2. it included an isolation valve so you can easily turn off your filter system for maintenance and carriage replacement. As a plumber I was very pleased with install. I am very picky in the way I put things together and it still only took me about an hour or so. I bet you could do the job in 30 minutes if you were in a hurry. Parameters: my tap water has any where from 250-400 ppm total dissolved solids (TDS). That's pretty standard for municipal water in southern California. still that is allot of stuff dissolved in the water including lead, arsenic, chloramine, and trace chemicals. Ph from tap is about 7.8. Coming out of the RO membrane before it hits the Alkaline cartridge I got a TDS of about 9-14 ppm. That is pretty incredible. the finished Alkalinity from this system was 8.8! perfect alkaline water. the mineral content was a great also, about 40-60mg/L of Carbonate hardness and 60mg/L general hardness. That means the perfectly minneraled and alkalized water free from chemicals, heavy metals or any harmful contaminates. The flavor as you can imagine is incredible. I use it to brew beer with, my friends cant believe the quality of my brew, the secret is the water. I use it to brew kombucha with similar results. I use it to fill my fish tanks, the African Cichlids need the high Ph. Finally the customer service for iSpring is impeccable. I bought a cartridge replacement and has some issues, customer service was quick to handle my issue and did not cost me a dime to make it right. these are the genuine replacment filters and they make the system work as it did the day I installed it

Perfect fit for our undersink RO, shipping fast. Was a good decision to add this equipment to our kitchen remodel. Per instructions easy to change filters. Comes with new fittings if needed. I didn't use them but was nice that they were in the box. With no leakage. With that they are OEM replacement, functionality Perfect and materials seemed to be well made.

Me gusta la calidad de estos cartuchos de repuesto, además que son más fáciles para cambiar en la purificadora.

خاضعة للمواصفات الامركية انصح بها لمن يبحث عن الجودة 👍

Ho acquistato il set di cartucce iSpring F9K come ricambio annuale per il mio sistema di filtrazione, e la differenza si sente subito. Dopo l’installazione, l’acqua è tornata chiarissima, senza odori e soprattutto buonissima da bere. Il montaggio è semplice e tutte le cartucce si inseriscono senza difficoltà. Anche il flusso dell’acqua è rimasto costante, senza cali di pressione. Per l’uso domestico quotidiano è un kit davvero completo e conveniente, perché permette di coprire l’intero anno senza dover acquistare filtri singoli. In sintesi, sono ricambi affidabili e fanno esattamente ciò che devono: migliorare il gusto dell’acqua in modo evidente.

Je recommande aux personnes dont l’eau potable contient des substances organiques indésirables, l’eau qui en sort est excellente !

I am impressed with the simplicity of changing your own filters. So much cheaper than having water depot people install and service. The water tastes good and I can be confident I am not consuming lead.