iSpring F6K75 NSF Certified Replacement Under-Sink Water Filters, 6-Stage Reverse Osmosis RO Water Filtration Systems with Alkaline Mineral Filter, 6-months Replacement Supply Set, 6 Count (Pack of 1)

This under sink 5 stage RO system went together easily with the help of the manual and is currently working quite well. A number of little things, like the spare parts kit and the leak sensor cutoff switch are a nice touch. The first stage sediment filter clear housing is a must and seems to only be included in this brand. Overall quality is excellent and the full color pictures with little installation hints were great. Some minor howevers...However, there are a couple of items that can be improved, although they don't directly affect the performance of the system. One is the sheer bulk of the system (and any other RO system of this design). For dual sink installations where you have two sets of drains - and possibly garbage disposers, the system will not fit under the sink in all cases - mine was one. The main problem is the pressure tank. If you have a cabinet next door to the sink that you can give up some space, then the tank can go there. Otherwise it could be a deal breaker. This should be explained at the beginning of the manual and should give a footprint diagram and state: "STOP! Before you unpack our system...". This could simply be an added sheet laying in the top of the package.Second, the tool list is basic and you'll need other tools depending on the installation. Buy the optional slide-out rack is a must unless you plan to unmount the entire RO system occasionally as it will be impossible to change filters under the sink, especially the RO membrane. I ended up installing mine in the utility room with the faucet mounted on my laundry sink. This would be true of any RO system of this design. Not something explained on Amazon web pages for any system I looked at.Third, the manual gives a great description on how to prepare the leak sensor feedwater cutoff device, but they omitted to tell you where to put it and which line to put it in. I added the term "feedwater" because that's the line you put it in. It should be placed in the bottom of the sink cabinet under the RO system to detect leaks from the various push-in connectors that wet the cabinet floor. That should be thoroughly explained and seems to have been missed.Fourth, this system on my pressure well pump with 50-65 psi pressure switch, produces about 20 gallons a day, not 75 as advertised on Amazon. Real specs are actually spelled out in the manual and are accurate there. Not sure why they are advertising 75 GPD. The RO water to waste water ratio is not 1.5:1, which sounds amazing. It is closer to 1:1.5, which is closer to what I have read, about RO systems and is actually quite good for a non-boosted system. Although this is what I expected, it is something to be aware of if you are using it heavily and are paying for your water.A note on the above performance: my TDS (total dissolved solids) is lab tested at about 280 ppm for calcium compounds. This is high, resulting in very hard water, and will slow down RO water production. Also, running the system on a constant regulated higher pressure of 65 psi will improve the RO ratio and production performance. If you're not sure the RO system is working, without a TDS meter, just taste the waste water. (be careful if you suspect high levels of contaminants). Mine tastes like you dissolved a stick of chalk in it - imagined. The RO water is refreshing and clean.Overall, the system is excellent. The USA based company is one reason I chose this system. Although I have not had to use their help, other reviewers did and got good service. I highly recommend this system and their USA based company iSpring.

We love our RO water filtration system. It was installed under the sink back in 2018. We replace the filters on schedule. Very easy to do. Takes about 15 minutes. The RO water filtration system works great. Clean clear water at your sink. Great solution vs buying bottles water. If you have questions, call Sean at iSpring Filter. He is great to work with. Answers your questions. Gives you great advice on how to maximize the value of your water filtration system. We also purchased a Whole Home Water Filtration System from iSpring Filter in large part thanks to Sean's great customer service.

I’ve purchased these at least 4 times now and continue to buy when I need it to replace the filters to myself or my family. Great value for the money.

Good product

Quality product, very good priced. Arrives promptly via Amazon.Installation: originally installed by a licensed plumber, in a basement crawl space. Replacing filters: Stages 1,2,and3 are quite easy to change, and are the ones changed most often. Stage 4 is a bit more involved to change, but still not too difficult. Stage 5 is the hardest one to change, due to its location, and having to remove the entire filter from the water lines. The design in my opinion, to replace Stage 5 could be improved to make it easier for the customer to do. They use quick fittings on this stage. The instructions leave out one very important thing- how to disconnect the tubing from the fitting! I had to call customer service- it was a Saturday, they were closed. I left a message and they called back promptly on Monday. Spoke with Nick, who was very courteous and helped me with how to do the change. There were two small oval rings between the filter and where the tubing is connected. In order to release the tubing, you have to push the oval rings IN and hold, while pulling the tubing OUT! Such a little step, but one that makes it all work. After getting quite wet trying other ways, getting leaks, this correct way went smoothly and no leaks. Thanks Nick for helping me out.The installation videos from iSpring are good and easy to understand, however I didn't see anything about these quick fittings and how to do this step on them. (also, in the kit, it had Stages 1-4, but you need to order Stage 5 separately) And, in the main kit, you get extra fittings, but they are somewhat hidden in the box, and the kit list doesn't show them.

I bought this filter set for my iSpring RO100. One hitch, the new stage 5 filter inlet and outlet is smaller. See attached photos of the original (right) versus the new (left). This is a problem because the original hoses do not fit. The good news, I reached out to iSpring customer service, and yes I spoke to a live person, Michele, and she offered to send me the correct stage 5 filter as a one time courtesy. She also said to make sure for future orders, be sure it's for US. Within a few days, my new filter arrived and it fit, no issues. Overall, very happy with iSpring quality, longevity, and customer service. I've had Brita, Whirpool, and other under sink filter systems, and this is by far the best of all of them. Thank you Michele at iSpring.

I installed a reverse osmosis system under my sink about six years ago and I love it! It is the best tasting water, bar none! I also have a Keurig coffee machine that I used to have to de-scale about every six months, and I have not had to descale it ever since I put the system in. A couple of months ago the bladder in the tank began to fail, and John at the i spring company sent me a new tank free of charge. Could not be more pleased.