iSpring RCC7AK RO System [Alkaline Remineralization]

The iSpring RCC7AK is an upgraded version of the RCC7 model with the addition of a nice extra filter. It can filter out all types of contaminants and enrich the water in the same process giving you a healthier, natural-tasting, clean drinking water.

Excellent Filtration Process

The RCC7AK features multi-layered filtration process designed around 6 very efficient filtration stages specially tailored to progressively remove all types of contaminants and improve the water quality.

The first three stages are pre-filters consisting of polypropylene sediment filter in the 1st stage, GAC filter in the 2nd stage and a carbon block filter in the 3rd stage.

These three filters trap all the sediments and particles that are larger than 5 microns and more importantly removes chlorine, chloramines and other chemicals present in the water.

The fourth stage where the magic happens sits a quality RO membrane which eliminates all the remaining contaminants down to 0.0001 microns leaving behind only pure water.

A fine GAC filter takes the fifth stage and where the water from the RO tank is further polished to remove any residual contaminants from the tank.

Restoration of Lost Minerals

After going through the initial 5-stage RO filtration process, the RCC7AK includes a 6th stage which consists of an alkaline remineralization filter.

The standard 5 stages produce clean, pure water with all the contaminants removed as well as the few helpful minerals present in the water.

This 6th stage is a big plus as the alkaline filter restores the healthy minerals lost due to the RO process. The AK filter features red mineral stones which add back calcium and other essential minerals such as magnesium and potassium.

The filter also has a calcite portion that helps raise the pH levels of the RO water hence creating a much natural alkaline balance in the water.

Therefore, you not only get the benefit of drinking clean, purified water but you are also assured of getting some healthy minerals as well and a better, more natural taste.

RO water is so pure and as such it often tastes unnatural, but with this alkaline filter in place, your water will certainly taste much better.

Furthermore, the filter is made up of only natural mineral stones that serve as the filtration media hence your body will have no problem absorbing the restored minerals directly.

Filtration Capacity

The filtration capacity of RO membrane of this iSpring RCC7AK model is also quite decent for an under-sink residential RO system.

It’s capable of producing up to 75 gallons of filtered water a day which is sufficient to handle the water needs of small to medium-sized families whether it’s drinking or cooking.

Moreover, the system is relatively efficient as for each gallon of pure water produced, it wastes only 2 gallons which is really a mean feat for most filtration systems.

Installation and Maintenance

Featuring quick fittings, a cabinet fitted bracket and a clear, well-organized manual and videos, installing the RCC7AK is quite easy, especially if you have some little DIY skills.

All the parts you need including the pressurized tank, faucet, drain saddle, feed water adapter, tank valve and tubings are provided alongside the filters, membrane and the RO frame itself.

The system will easily fit under any standard kitchen sink and the overall construction is quite solid. The filters are durable too with the first three pre-filters requiring replacing just twice a year and the two post-filters requiring changing once a year.

The membrane will last 2 to 3 years based on the quality of your source water. Noise won’t also be a major problem like in other systems. The unit runs smoothly producing the least sound possible. 

All in all, the iSpring RCC7AK is a well-designed RO system with an effective 6-stage filtration process that eliminates all kinds of contaminants from the water and replenishes it with essential, natural minerals.

It’s definitely a win-win investment for anyone looking for an affordable system that can deliver a more natural tasting and healthier filtered water.


  • Efficient filtration process ensures crisp, clean, drinking water
  • Restores healthy minerals to the water and improves its pH balance
  • Decent filtration capacity and pure to wastewater ratio
  • Durable stainless steel construction 
  • Easy installation with a convenient noise-free operation
  • Backed by one year warranty plus a one-year money-back guarantee


  • That automatic shut off valve seems a bit flimsy
  • May need some DIY skills for easy installation

Read moreiSpring RCC7AK RO System [Alkaline Remineralization]

iSpring RCC7AK-UV 7-Stage Reverse Osmosis System

The iSpring RCC7AK-UV is yet another top-notch model within the iSpring RCC7 series. It’s the variation of the iSpring RCC7AK model offering the same great RO system that features a remineralization filter but with the addition of a UV light filter. 

iSpring RCC7AK-UV is a deluxe multi-layered reverse osmosis system that provides optimal protection against more than 1,000 different types of contaminants including arsenic, asbestos, chlorine, hormones, fluoride, lead, mercury, sodium, bacteria, giardia, viruses and more.

The RO system consists of 7 processing stages, the first 6 stages work similarly to the previous system RCC7AK, the 7th stage is an 11W UV bulb as an additional protection layer that against the variety of microorganism that past the RO filter.

Filtration Process

The RCC7AK-UV comes equipped with 7 filtration stages which makes it one of the most comprehensive RO systems from iSpring and one that guarantees the best water quality possible.

The initial 5 stages consist of the standard iSpring’s 3 pre-filters we’ve seen in the other models and they remove all large contaminants down to 5 microns and chemicals particularly chlorine and chloramines.

They are followed by the 0.0001-micron RO membrane that removes up to 99% of all the remaining contaminants. The fifth stage is a finer GAC filter which gives the RO water the final polishing as it leaves the RO tank.

After passing through these initial 5 stages, the RCC7AK-UV model incorporates two more stages comprising of an alkaline remineralization filter and a UV sterilization filter.

Sixth Stage – Alkaline Filter

The 6th stage of the RCC7AK-UV uses an alkaline remineralization filter which is made up of red mineral stones that restore the healthy minerals removed from the RO water by the initial 5 stages. It adds back calcium, magnesium, potassium, and sodium.

The filter also has a calcite portion which helps raise the pH level of the RO water to natural alkaline balance giving a better and more natural taste. This is essential as the RO filtration process reduces the pH value of the water making it tastes slightly acidic.

Seventh Stage – UV Sterilization Filter

The final stage in this RCC7AK-UV system features a UV sterilization filter that offers an additional level of protection from possible microorganism contamination.

The filter uses a powerful 11W UV lamp which emits UV light as the water passes through it. The UV light kills 99.99% of harmful organic microorganisms that might seep past the RO filters including bacteria, protozoan cysts and viruses.

To ensure great efficiency, the unit comes with a smart flow sensor switch too which turns off the UV light once the water is not flowing through it thereby saving power. The UV lamp also comes in a protective stainless steel housing to ensure its durability.

Filtration Capacity

The RO membrane of the RCC7AK-UV can deliver a maximum of 75 gallons per day. The capacity might vary though based on your source water pressure and temperature but it’s able to meet the needs of most small to medium-sized families.

The system, however, wastes around 3 gallons of water for every one gallon of clean water it produces. Considering that most of the other iSpring’s model has an average ratio of 2:1, this one will slightly waste more water unless you install a booster pump alongside it.

Installation and Maintenance

As with the other iSpring models in our list, the RCC7AK is not that hard to install yourself if you have basic DIY skills. Everything you need to set it up is provided and the instruction manual is user-friendly with pictures and illustrations that make it easier to understand and follow. The whole unit is compact and will nicely fit under any standard kitchen sink.

Overall, the quality, performance, and features of this RO system are really commendable. By combining both the alkaline and the UV lamp filter means you are always assured of clean, healthy water that has a much better and natural taste throughout.

It’s a system we would highly recommend for anyone wanting a unit that offers more than just the standard RO filtration process.


  • Removes more than 1000 different contaminants
  • Alkaline filter restores healthy minerals and raises pH
  • UV filter to help kill harmful microorganisms in the water
  • Flow sensor switch helps keeps power cost low
  • Up to 75 gallons of clean water output per day
  • Relatively easy to install and operates quietly
  • Comes with a 3-year limited warranty plus a 1-year money-back guarantee


  • Wastes 3 gallons of water per 1 gallon of clean water which slightly above average
  • Low source water pressure may affect production capacity and speed

Read moreiSpring RCC7AK-UV 7-Stage Reverse Osmosis System

iSpring RCC7D RO System Reviews

The iSpring RCC7D is an RO deionization filtration system specially designed for anywhere that ultra-pure water with zero total dissolved solids (TDS) is required.

It provides complete water purification via six individual filtration stages that include a specially manufactured deionization (DI) resin filter which makes a superb option for either aquarium use or drinking water.

Filtration Process

The early filtration stages of the RCCD7 are the same as the RCC7 and the other iSpring RO systems.

The five stages feature the 3 carbon pre-filters that capture large contaminants and volatile organic carbons in the water. They as well ensure chlorine, chloramines and other chemicals are removed in the water ahead of the RO membrane.

The TFC RO membrane completely removes all the contaminants that are larger than 0.0001 microns while the fifth stage coconut shell post-filter further captures any residual chlorine and chloramines that sipped through the RO membrane.

Deionization Filter

The last stage of the iSpring RCC7D is the specially designed deionization resin filter and it’s what sets this model apart from most other similar systems in out there.

It’s a super-efficient deionization post filter which completely removes the total dissolved solids (TDS) in the filtered water that the RO membrane could not capture.

It effectively uses ion exchange resins to clear all the dissolved contaminants bringing the water to 99.99% purity with close to 0 ppm TDS.  

In other words, it delivers the purest water possible, even purer than distilled water which makes the RCC7D ideal for use in aquariums, laboratory testing, and cleaning.

The water produced by the system is also safe for drinking, but considering that all the TDS and minerals are completely removed, it may taste plain or unpleasant to most people.

However, if your tap water is hard and you don’t mind the taste, then you can certainly use this system to soften your tap water hardness level and produce clean and highly pure drinking water.

Filtration Capacity

With regards to filtration capacity, the RCC7D will give you a maximum of 75 gallons of clean water per day which is sufficient for larger freshwater aquariums, reef aquariums, and fish breeders.

It’s as well enough for small to medium-sized families if you are using it for drinking water. It wastes around 2 gallons for every gallon of water it produces, so it’s equally quite efficient.

Installation and Maintenance

The installation process for the RCC7D can be a bit confusing but the instruction manual is clear and well organized plus there are videos that guide you through the process. All the parts are included and the unit is small enough to fit under most standard kitchen sinks.

In general, we would highly recommend the iSpring RCC7D to anyone who is looking for a system that can give them the purest water with almost zero TDS value.

The combination of the RO filtration process and the deionization filter will absolutely give you clean, clear and water with maximum purity possible ideal for your aquarium or drinking.


  • Captures all the contaminants including chlorine
  • Super-efficient deionization filter clears all the dissolved contaminants
  • Fairly large filtration capacity of 75 gallons a day
  • Suitable for drinking water, aquarium and applications that need pure water
  • Everything required for the installation is included
  • Relatively easy to install and comes with 1-year limited warranty


  • Produces ultra-pure water which may taste plain

Read moreiSpring RCC7D RO System Reviews

iSpring RCC7P-AK RO Filtration System Review

The iSpring RCC7P-AK is exactly identical to the RCC7AK model except that it comes equipped with a booster pump making it an ideal choice for those households where the feed water pressure is below 40 psi.

Filtration Process

Like the RCC7AK, this unit is a 6-stage reverse osmosis system with the first three stages offering a combination of three prefilters with polypropylene sediment filter in the 1st stage, GAC (KDF) filter in the 2nd stage and a carbon block filter in the 3rd stage.

Together they remove all large contaminants down to 5 microns as well as chemicals such as chlorine and chloramines. They also remove any unpleasant odor and tastes in the water.

The fourth stage RO membrane eliminates up to 99.99% of all the remaining contaminants in the water down to 0.0001 microns which include fluorides, arsenic, lead, bacteria, viruses, VOCs and much more.

In the fifth stage is a fine GAC filter that removes residual contaminants from the RO tank. The final stage is an alkaline remineralization filter comprising of minerals stones and calcite media.

The filter restores the healthy minerals (calcium, magnesium, potassium and sodium) into the water while raising its pH to give purified water with a more pleasant natural taste.

Booster Pump

If your source water pressure is low (below 45psi), then the iSpring RCC7P-AK model will solve this problem as it features a built-in booster pump that can raise the pressure up to 80 psi.

By boosting the pressure, the pump ensures the system works effectively regardless of any pressure variations and as well improves its production speed.

Filtration Capacity

The iSpring RCC7P-AK RO membrane can produce 75 gallons of water every day which is enough to meet the daily water demands of small to medium families. 

The tank can hold up to 3.2 gallons which pretty much a standard capacity for almost all the tanks that are included in iSpring’s RO systems.

For each gallon of purified water it produces, the unit wastes around 2 gallons, so it’s equally fairly efficient like its counterpart the iSpring RCC7AK above.

Installation and Maintenance

When it comes to installing this RCC7P-AK model, it’s a quite a straightforward DIY process provided you have some technical skills.

All the necessary parts and tools for installation are included plus a clear manual and you can even get instructional videos in YouTube to guide you through the whole process. The unit is 19 inches tall, so it will fit under any kitchen sink with a 21” space in height.

Maintenance is as well a breeze. The pre-filters and the AK filter require replacing every 3 to 6 months. The RO membrane will last 2 to 3 years while the fifth stage filter can go for a year before requiring replacement.

The pump and the system operate nearly noiselessly such that you can barely hear any sound over normal kitchen activity. It won’t cause any disturbance at all plus the pump automatically turns once the tank is full.

If there’s any set back to point out it would probably be the fact that the service life of the prefilters is a bit short especially in case of very hard water. Other than that, this is a great reverse osmosis system to consider for those with low source water pressure.


  • Removes 99.99% of all contaminants in water
  • Restores the natural minerals and alkalinity of water
  • Booster pump increases pressure to optimal levels
  • Delivers 75 gallons of water a day
  • Installation is fairly easy and the system operates quietly
  • Comes with one year warranty and a one-year money-back guarantee


  • The prefilters are not that durable

Read moreiSpring RCC7P-AK RO Filtration System Review

Watts Premier 521934 Six Stage Reverse Osmosis System

Concerning filtration performance and production rate, the Watts Premier 521934 model takes the upper hand compared to the rest of Watts Premier RO systems featured on our list. This unit is a top performer offering a very fast production rate and remarkable filtration process designed to ensure the purified water generated is of high quality.

Filtration Process

The Watts Premier 521934 has 6 stages of filtration consisting of three pre-filters, two parallel flow membranes and a post-filter all working together to make sure the water is thoroughly purified.

The 1st stage is a 5-micron sediment filter that traps the fine particles and larger sediments such as dirt and sand to protect later filters from getting clogged. 

It’s followed by a 5-micron carbon block filter made from coconut shell in the 2nd stage which is the first point where chlorine and other chemical contaminants like chloramines and VOCs are extracted from the water.

The water then goes through a second 5-micron carbon block filter in the 3rd stage also made from coconut shell and this provides additional reduction of the remaining chlorine and chemicals while as well acting as the pre-filter to the RO membranes.

The 4th and 5th stages feature two parallel flow RO membranes which allow the system to perform double filtration. This one of the features that make the Watts Premier 521934 a highly effective water purification system.

These quality membranes filter the water down to 0.0001 of a micron basically removing 99% of the contaminants which includes TDS, microorganisms, heavy metals and natural organic compounds.

Taking the 6th is a granular activated carbon (GAC) post-filter which is the final stage in the system and serves as the last polishing filter right after the water leaves the storage tank. It clears out any residual chlorine, tastes or odor in the water before it’s dispensed out of the faucet.

Filtration Capacity and Efficiency

The best part that puts this Watts Premier 521934 model ahead of the rest is the exceptionally fast production rate it offers especially since it’s a standard under sink reverse osmosis system.

The two parallel RO membranes each produce up to 75 gallons of purified water per day which is not only an adequate capacity for those who use large amounts of water regularly but provides a much faster water production rate than RO systems that utilize only one 150GPD RO membrane.

Having a single filter is good, but two is much better because it translates to faster purification times as well as a more continuous flow of water plus the unit comes with a large, space-efficient 4-gallon RO storage tank offering more than enough capacity to ensure a regular supply of water.

This is a perfect unit for large families as well as corporate environments like offices or small businesses. It can comfortably handle pressures of up to 150 psi.

Installation and Maintenance

The process of setting up this high-performance Watts Premier model is fairly easy if you have some basic DIY skills. You just need to follow every step in the installation manual dutifully and you will it up and ready to run in less than 2 hours.

The two parallel membranes will give you a service life of 2 to 5 years. For the pre-filters, you will need to change them after every 6 months and the post-carbon filter once every year.

To sum it all, Watts Premier 521934 is a unit that offers great value for money. It’s not only a highly effective water purification system due to its double filtration but it also comes at an incredibly reasonable cost. You will certainly not be disappointed if you have a large family.


  • Double membrane design for optimum filtration performance
  • Very fast production rate with adequate capacity for larger families
  • Big 4-gallon holding tank facilitates a constant supply of purified water
  • Setting it up is fairly easy as well as changing the filters
  • Backed by a 1-year limited warranty


  • May not work well in areas with low feed water pressure

Read moreWatts Premier 521934 Six Stage Reverse Osmosis System