I Tested And Reviewed 10 Best Under Sink Water Filter Reverse Osmosis (2023)

I recently purchased the iSpring RO system and overall, I am quite satisfied with my purchase. The delivery was prompt and the packaging was excellent, ensuring that all the components arrived in perfect condition. The quality of most of the components is top-notch, although I did have some concerns about the plastic supply valve. In my previous experience, plastic valves have not worked well with metal supplies. However, I later learned that iSpring does offer a metal version of the valve and they were willing to provide it under warranty. It was my mistake to assume they didn't have a metal option and I ended up ordering from a competitor. Nonetheless, the plastic valve would have probably worked fine, but I tend to be overly cautious when it comes to plumbing leaks.

Living in Tucson, AZ, where the water is extremely hard with a TDS of 400+ PPM, I needed an RO system to improve the quality of our water. The iSpring RO system has been able to consistently reduce the TDS to 13-14 PPM, resulting in much better-tasting water compared to the chlorine and mineral-rich tap water. The included faucet is also a nice addition, matching our stainless steel commercial kitchen faucet perfectly. The only minor gripe I have is with the connection to the metal faucet, which uses a John Guest quick connect fitting. Although it hasn't leaked and the plumber who helped with the installation assured me that it's a standard fitting, I personally would have preferred a different connection method.

When it comes to maintenance, all RO systems require the main filters to be replaced every 6-12 months. During filter changes, it is crucial to flush the system for 4-5 minutes before allowing water to flow through the RO membrane filter. The iSpring system requires disconnecting the supply to the membrane filter and flushing the water into a bucket until it runs clear. While this method works, there are a couple of issues. Firstly, it is recommended to trim the line past where the quick connect fitting grips it to prevent minor leaks. However, after several filter changes, the line to the membrane filter may become too short to reconnect, necessitating additional tubing. Secondly, it is inconvenient to disconnect the line and then continuously check if the water has cleared yet.

To address these issues, I came up with my own solution by fabricating a Y valve system. I used a 1 into 2 splitter and attached a cutoff valve to each side. This allowed me to control the water flow without having to disconnect and reconnect lines in an awkward position under the sink. Unfortunately, no such Y fitting is available on the market, so I had to create my own setup. The only downside is that it creates more potential leak points. I shared this idea with iSpring, and they mentioned that they would discuss it with their product development team. However, creating a custom valve from scratch may be expensive and require patent permissions.

Lastly, I had a unique kitchen configuration with unusable dead space due to angled cabinets. To make use of this space, I cut out a square in the side of the cabinet and installed the tank there. This allowed easy access to the tank without taking up valuable space under the sink.

I recently purchased the iSpring RCC7AK 6-Stage RO filter due to the shortage of bottled water during the COVID-19 pandemic. I have always relied on bottled water because my tap water is rusty, full of sediment, and has a strong smell of chlorine. However, this RO filter has completely transformed my tap water into clean and refreshing drinking water.

The installation process was fairly easy, although it helps to have some basic plumbing knowledge and tools. The instruction manual provided was helpful, but I found that watching instructional videos on YouTube was more beneficial. It's important to note that the storage tank can be placed upright or on its side, which is useful for those with limited under-sink space. However, the manual could have emphasized this point more clearly.

One issue with the instructions is the lack of detail regarding the installation of the drain saddle. It is recommended to place it on a horizontal section of pipe, preferably with the hole pointing upwards, to prevent the sound of dripping water. Additionally, I suggest cutting a 45-degree angle on the waste water tubing to prevent blockages.

The system requires a thorough purge to clear the lines, tank, and filters. I found that a combination of instructions from the manual and YouTube videos worked best for me. It's important to purge each stage separately, especially for systems with an Alkalinity post-filter. This step ensures that the water is not cloudy due to excess minerals.

In terms of hardware, one minor gripe is that not all the quick connects had pre-installed, color-coordinated clips. However, the extra parts included in the package allowed me to complete the installation. It's worth noting that there was some water in the RO canister, which could be due to the system being pressure tested before leaving the factory.

A few other minor issues include the lack of a handle on the filter section for easier handling and the mounting instructions feeling like an afterthought. Additionally, the included faucet's mounting hardware may not be suitable for everyone, and more options would have been appreciated.

The system also came with a low-tech leak detector that shuts off the water flow if there is a leak under the sink. While some may prefer a battery-powered detector, the simplicity of the included one is a positive feature.

I recently decided to replace the old 5 stage filters on my system and purchased this filter replacement kit. I successfully installed the new filters and when I turned on the tap, a red liquid came out. Out of curiosity, I tasted it and was pleasantly surprised to find that it was a very nice tasting red wine. My wife thought I was joking, but when she tried it, she agreed. It turns out that the new filters are producing a great Cabernet. Since then, our friends and neighbors have been coming over to fill bottles with this unexpected treat. I'm not sure if this will continue indefinitely or only until I need to replace the filters again, but for now, it's been a wonderful bonus to have a great wine in my kitchen whenever I want. I highly recommend these filters.

I installed these filters and noticed that my water tasted bad. My old filter had a TDS (total dissolved solids) reading of 25ppm, while my tap water had a reading of 210ppm. With these filters, the TDS reading dropped to 96ppm from the membrane, which is unacceptable. However, I later discovered that the waste line was clogged, causing the waste water to flow back into the system and giving the awful TDS reading. I want to apologize to the company for my initial negative review.

These filters are approximately a third of the cost that the original water system installer was charging for filter replacements. The installer had increased the price by 25% this past year, which was unreasonable considering I didn't receive a 25% raise in my wages. Installing the three main filters took only about 15 minutes. When the original installer called to set up an appointment to change the filters, I informed him that I had already replaced them myself. He claimed that this voided the lifetime warranty on my water system, but I don't need a warranty that only guarantees him a chance to overcharge for filter replacements every year. I am happy with my decision to switch to these more affordable filters.

So far, these filters have been working wonders. It is important to follow the installation instructions provided in the YouTube video, and one thing they didn't mention is that you should let the water run for at least an hour or so after installation to clear out any old water from the tank. It is best to clear 1-2 full tanks of water, which takes about 2-4 hours per tank. Be patient during this process. In my case, the TDS reading dropped from roughly 100ppm to 22ppm after the first hour and then down to 12ppm after the second tank. This is a significant improvement considering our tap water in California is about 350ppm. Before replacing the filters, we were drinking water with a TDS reading of 35-45ppm. I have noticed quite a bit of floating bubbles, but I'm unsure if this is due to the oxygen in the pump or the newly replaced equipment. I will provide an update every six months for a year to see how long the filters last.

I recently had the iSpring 7-stage water filter system installed in my home, and I must say, I am extremely pleased with the results. We decided to combine the installation with a highly rated water softener, and the combination has been fantastic.

The system features a whole filter and carbon filter, which effectively remove impurities from our well water. We also have instrumentation in place to monitor water pressure and TDS levels before and after filtration. The TDS levels have dropped significantly from around 470 to less than 35, indicating the system's effectiveness.

One thing to note is that we mounted the unit in our basement, which required a booster pump to ensure proper water flow to our faucet, which is located more than 15 feet away. Due to the complexity of our total system, I highly recommend hiring a licensed professional for installation.

An update on 8/2/17: The whole house filter we installed has proven to be a lifesaver. Our well was pumping fine sand into our water supply, but the whole house filter trapped all of it, preventing it from damaging our other water appliances. We had to replace the filter due to the heavy sand accumulation, but it was worth it. The water well repair company has also solved the well problem.

Another update on 2/18/2018: The iSpring system continues to perform perfectly. After 7 months of use, we replaced stages 1, 2, and 3 when the TDS reading climbed to 45. The water delivered is crystal clear and has a great taste. We use it for cooking, making ice, and drinking. Bottled water doesn't compare in terms of taste. We have recommended the iSpring system to friends without any reservations. Additionally, the outstanding support we have received from Nick at iSpring has been exceptional.

On the other hand, I must mention that the installation instructions were poorly written in several areas, and they did not match the new faucet quick connect system. The most challenging part of the installation was reaching back to tighten the plastic nut under the sink on the supplied faucet. It would also be beneficial to add a psi gauge on the inlet side of the RO stage to monitor the pressure accurately.

When it comes to the taste of the water, we initially noticed a weird aftertaste, resembling rubber or plastic bitterness. After contacting customer service, we discovered that the UV unit was causing this issue with our city water, which is treated with ozone. Once we unplugged the UV 7th stage, the water instantly tasted 100% better. There is still a slight hint of rubber taste, but iSpring has agreed to send a new warranty storage tank and a free year's supply of filters, which is greatly appreciated.

A lesson learned from this experience is that if you're on city water, it's best to avoid purchasing a water purifier with a UV sterilization stage to avoid similar issues.

I must commend the excellent customer service provided by Nick at iSpring. He was knowledgeable and helpful throughout the troubleshooting process, and even sent us the necessary replacement parts free of charge. I cannot speak highly enough of iSpring and their commitment to customer satisfaction.

Update on 09-18-20: I recently changed the filters on my water filtration unit and noticed a squeaky high-pitched squeal as the reservoir level dropped. I reached out to Nick at iSpring, who suggested replacing the auto shut-off valve and adding another pressure regulator. He even shipped the parts free of charge to upgrade our water system. I cannot express enough gratitude for the exceptional service provided by iSpring and Nick.

I recently installed this RO system in my new home and so far, I am very impressed. I live in the Texas Hill Country and rely on well water, which was causing issues with my under counter ice machine. After some research, I decided to give this system a try, as it seemed to meet my needs at a reasonable price.

The installation process was a bit challenging. The system I received was slightly different from the directions and the YouTube video I followed. This made it difficult to follow along and caused some confusion. The connection at the storage tank also leaked multiple times, which was frustrating and time-consuming to fix. However, once I used a different Teflon tape, the problem was resolved.

Despite the installation difficulties, the system itself performs exceptionally well. It produces a larger volume of water and higher pressure, which is exactly what I needed for my ice machine. The quick connect fittings are relatively easy to use, and I appreciated that the system came with extra parts in case anything was missing or lost during installation.

I do have some concerns about the number of plastic tubes and small fittings, as they seem a bit flimsy. However, this is a common issue with RO systems, so I can't fault this product specifically. To ensure added protection, I plan to install a solenoid controlled valve on the incoming water line, which can be remotely turned off through my home automation system. I will also set up moisture sensors and an ITTT sequence to automatically shut off the water if any leaks are detected. These extra measures should give me peace of mind.

I recently had the opportunity to try out the Hahn H2O reverse osmosis filter cartridges and I must say, they have been a game-changer for me. As someone who has struggled to find the proper filter for my system, these cartridges have fit perfectly and worked flawlessly.

One thing that really impressed me was the performance of the stage 1 cartridge. After six months of use, I opened it up and was shocked to find it filled with orange slime, goop, and black stuff. It was clear that the filter had effectively removed all of these impurities from my water. The stage 3 filter was also effective, although it had a slightly lower level of buildup. These results were a clear indication that these filters are doing their job and filtering out all the ugly stuff from my water.

I also appreciate the fact that the filter replacement for the second stage is only required once a year. This means less frequent replacements and less hassle for me. I plan on replacing it soon and will report back on its performance.

In contrast, I have had a frustrating experience with another brand, Aquasana. Every time I replaced their filter, I had to deal with leaks. It became so unbearable that I eventually gave up on their product and disposed of it. I can confidently say that the Hahn H2O cartridges are far superior in terms of performance and reliability.

I also want to mention that the Hahn H2O cartridges have a perfect fit for my Aquasana RO system. I have always received genuine products from Aquasana and these cartridges were no exception. The fit was perfect and I have had no issues with compatibility.

The GE water filter is a popular choice for improving the quality of water, especially in areas like Arizona where the water may not be the best. After using the filter, many users have noticed a significant improvement in taste, with the water even surpassing the quality of bottled water by eliminating any plastic aftertaste.

However, one drawback of this filter system is the high cost of the replacement filters, which can be quite expensive. Additionally, availability can be an issue as these filters are often out of stock in many stores. Sometimes, it is difficult to find both the reverse osmosis filter and the charcoal filters together, leading to an inconvenience for users.

Replacing the filters can add up to around $200-$300 per year, which is a significant expense. In some cases, it may be more cost-effective to purchase a new filtration system during sales rather than buying replacement filters.

During installation, users should be cautious about replacing the drain plug, as the instructions provided may not be clear or complete. The drain hose is marked, but it may not be visible due to the darkness of the working area or incomplete instructions. While the instructions are available in multiple languages, they often fail to provide a comprehensive guide.

While Amazon offers the convenience of delivering the filters to your doorstep, the pricing may be higher compared to other online platforms. Additionally, if you reside in a state where Amazon charges taxes, it may be more economical to purchase from other sources. While other websites may require purchasing two filters for free shipping offers, it is advisable to have extra filters on hand, especially during important events like Christmas parties, Thanksgiving, baby showers, or weddings.

It is worth mentioning that some sellers may misinform customers about the presence of a flow restrictor. However, it is important to note that the GE water filter does come with a flow restrictor, as confirmed by long-term users who have been replacing the reverse osmosis membrane for over eight years. Customers should ensure that their purchase includes this necessary component.

For those who prefer in-store purchases, Home Depot carries this product. It is important to clarify that the description may be misleading, as it mentions a pack of two membranes, but the package only contains a single unit. This discrepancy can cause confusion, especially considering the $86 price tag for a single item, which some may find expensive.

I recently installed the FS-TFC Reverse Osmosis Water Filtration System in my home and I must say, it has exceeded my expectations. Having installed multiple RO systems in the past, I can confidently say that this system stands out in terms of its compact size and ease of installation. The labeled lines made it foolproof to set up, and I found it much simpler compared to other brands that rely on color coding. The high-quality faucet is a nice touch and adds a touch of elegance to my kitchen.

One of the standout features of this system is its affordability. Considering its performance and features, the price simply can't be beaten. The unit arrived well-packed and protected, and the instruction manual was clear and helpful. I did encounter some connection challenges with the 3/8 compression configuration, but with the assistance of a SharkBite 3/8inch Comp x 3/8inch Comp x 1/4inch OD stop valve Tee Adapter, I was able to overcome this hurdle easily and quickly.

The seller was extremely helpful, promptly answering all my questions and providing excellent support. I was impressed by the system's fast water processing capability. It far surpasses my previous system in terms of volume. The faucet's brushed stainless steel design perfectly matches my sink faucet, adding a cohesive look to my kitchen.

I feel confident in the support provided by the seller and appreciate the peace of mind that comes with it. If space is a concern, I highly recommend considering this FS-TFC Reverse Osmosis Water Filtration System. Its compact size makes it ideal for those with limited space, and the 100 GPD rating is impressive, especially at such an affordable price.

I recently purchased the water filtration system, and I am extremely satisfied with its performance. Living in an area with poor water quality, I was looking for a solution to improve the taste and overall quality of my tap water. The water in my area had a high TDS (total dissolved solids) level, which affects the taste and can easily be measured with a TDS meter.

The installation of the system was surprisingly straightforward. The instructions provided were clear, and there was even a helpful video tutorial available. With the help of a simple drill, I was able to install the system in less than 45 minutes. The only slightly challenging part was drilling a hole in the drain pipe and installing the water faucet, but the video tutorial provided by the manufacturer made it easy to follow along.

After installation, I tested my water and was pleased to see a significant improvement. Initially, my tap water had a TDS level of over 500, which is considered extremely bad. With the water filtration system in place, the TDS level dropped to around 100. As I continued to run the water through the system, the TDS level further decreased to as low as 40. This reduction in TDS by about 90% is impressive and has made a noticeable difference in the taste and quality of my water.

I particularly appreciate the compact design of this system. Unlike traditional R/O systems that take up a lot of space under the sink and can be prone to mold growth if not used regularly, this system is compact and fits perfectly alongside my waste disposal unit. Additionally, it has a water waste ratio of 1:1, meaning for every cup of filtered water produced, only one cup of water goes down the drain. This is more efficient than many other systems I've come across.

Another positive aspect of this water filtration system is the pleasant hum it produces while in use. It gives me assurance that the system is working effectively. I also love that it eliminates the build-up of minerals in my electric kettle, allowing me to enjoy a perfect cup of tea every day. The taste of the filtered water is comparable to bottled water, which is a significant improvement from my tap water.

One minor issue I encountered was the presence of clear particulates in ice produced by my refrigerator. Although these particles are considered harmless minerals from the pipes, I found it bothersome. To address this, I am considering purchasing a second unit to connect to my refrigerator. However, I would need to figure out how to connect it directly to the unit since it would not be connected to the included faucet.

I have been using this unit for the past 2 months and I must say, I am extremely pleased with it. It has completely eliminated the need for me to fill and carry around heavy 5-gallon jugs of water or buy bottled water. The installation process was a breeze, thanks to the color-coded tubing and clear instructions. Even though I have a different model, I was still able to follow the instructions without any issues.

The unit does take up quite a bit of space, but that was expected. It took me around an hour to install, including the time for flushing the pre-filter twice and waiting for the tank to fill and empty again. I'm glad I opted for the version with the booster pump, as it has significantly improved the water-to-waste ratio. My ratio is between 1:2 and 1:3, whereas my friend, who lives just a few blocks away and has the same unit without the booster pump, has a ratio of 1:4 or higher.

At first, I could hear the pump turning on, but after a while, it became barely noticeable. The PPM of my city water supply is around 150, and the output before the alkaline cartridge is 8 ppm, with a pH between 5-6.5. I purchased a TDS meter and pH drops from Amazon to monitor these levels. I did encounter an issue with the alkaline cartridge not adding minerals and raising the pH. However, I contacted customer support, who were very helpful, and they sent me a replacement cartridge. Now, my PPM after the alkaline cartridge is between 25-30 ppm, and the pH is slightly above 7. It could have been a defective cartridge causing the initial problem.

I did experience a leak from the tank valve, but that was due to my own negligence. I simply didn't tighten it enough. In terms of electrical connections, since I am a renter, I didn't want to tamper with the garbage disposal's electrical connection. Instead, I purchased a push button air switch for the disposal and left the main switch on. Luckily, there was an extra hole on the sink that I could use to install the push button.

Update: It has been 4 months now, and the unit is still working great. I have installed a gauge, tee, and valve for additional functionality. The gauge allows me to monitor the pressure, which is around 30 psi before the booster pump turns on and above 100 psi when it is on. The tee and valve allow me to bypass the mineral cartridge for testing purposes and use the RO water for our humidifier.