If you are looking for an affordable under-sink RO system that produces mineral water, we recommend the iSpring RCC7AK reverse osmosis water filter.
It consists of 5 filters that can remove over a thousand contaminants plus a remineralization filter that adds back healthy minerals to the purified water.
With a daily production capacity of 75 gallons, the RCC7AK is perfect for most families.
Read on for our full review of the iSpring RCC7AK RO filter.
To compare the RCC7AK to other top RO systems, read our in-depth RO filter buying guide and reviews.
Filtration System Design
The RCC7AK has six stages, with one of those stages being a remineralization filter.
The filtration system design is pretty similar to other RO systems.
Water first flows through the pre-filters, goes through the RO membrane, goes to the reserve tank, and then passes through the post-filter and mineral filter on the way out of the faucet.
The only filter lacking is a UV filter. If you want an RO system with UV sterilization, get the iSpring RCC7AK-UV.
Here’s a more detailed description of each filtration stage.
The water first goes through a sediment filter. Here, suspended contaminants like sand, silt, rust, and dust are filtered out.
This clears water turbidity and ensures these impurities don’t clog up the carbon filter and RO membrane ahead.
The sediment filter has a clear housing that makes it easy to monitor filter life.
The next two pre-filters are both carbons.
The first is a carbon KDF filter. It consists of granules of activated carbon that absorb chemicals like chlorine, pharmaceuticals, pesticides, and hydrogen sulfide.
The KDF filter also filters out any remaining particles of sediment.
The second is a carbon CTO block that further filters out chemicals that affect the taste and smell of water. These include chlorine and chloramines.
The pre-filters play an important role in increasing the lifespan of the RO membrane. If chemicals like chlorine reached the membrane, they would damage it.
The semi-permeable membrane is at the heart of the system. It filters out the toughest and tiniest impurities, including microorganisms, dissolved minerals, and heavy metals.
Anything bigger than 0.0001 microns gets filtered out.
The RO membrane plus the pre-filters together remove over 98% of a wide range of contaminants including arsenic, fluoride, chlorine, lead, asbestos, hardness minerals, cysts, bacteria, and viruses.
A granular activated carbon (GAC) gives the water a final polish before it flows out of the faucet. This removes any odors and tastes the water may have picked up in the reserve tank.
It also removes any chemicals that may have escaped the other filtration stages.
Just before the water comes out of the faucet, it passes through a final filter containing red mineral stone.
The filter adds calcium, magnesium, and other healthy minerals back into the water.
This makes the water tastier and healthier.
Instead of the flat acidic taste of normal RO water, the RCC7AK produces natural-tasting mineral water.
If you’ve been used to bottled water, it will be easy to transition to this system.
Though cheaper than most RO systems, the iSpring RCC7AK is just as good as premium filters when it comes to filtration performance.
According to the manufacturer, the five filters remove over a thousand different contaminants.
The removal rate varies for different contaminants. But for most types of impurities, the RCC7AK can remove 98% or more.
One reason the RCC7AK is so effective at purifying water is its filtration system design.
In the pre-filter stage, it uses double carbon filters rather than just one.
This filters out many contaminants– specifically chemicals and fine sediment – before they even get to the RO membrane.
This leaves the membrane to focus on the hard-to-remove contaminants like germs and total dissolved solids.
The remineralization stage, while not essential to the filtration process, is a nice addition.
It improves the taste of water. Rather than the usual flat taste of acidic RO water, you get bottled-water quality water.
This is where the iSpring RCC7AK loses some marks.
Because it has no booster or permeates pump, it wastes more water than some RO systems. Mainly, it drains 3 gallons of water for every 1 gallon of purified water you drink.
Some of that water is not wasted per se. It’s used to flush the RO membrane to keep it from clogging.
But some of that waste is also due to back pressure from the pressurized reserve tank.
The iSpring RCC7AK has no feature or technology to reduce backpressure. That’s why it is less efficient than other RO filters.
If you want to reduce the amount of water wasted, consider installing an electric booster pump.
It will increase water pressure, which will counter the wasteful effect of back pressure. With a booster pump, the wastage will be 1-2 gallons.
Installation and Maintenance
The iSpring RCC7AK is relatively easy to set up though you’ll need to set aside around 1-2 hours for installation.
It has been designed for DIY installation.
The tubings are color-coordinated to make it easy to figure out where each tube goes.
The system uses push to connect fittings that don’t require any tools.
The part that consumes most of your time is drilling a hole in the sink for the faucet and, for the drain line.
Everything you need is included along with the filter. This includes a lead-free brass faucet with a beautiful brushed nickel finish.
Unless you want to upgrade to higher quality connectors and fittings, you don’t need to buy anything extra to install the RCC7AK.
The user manual has very clear instructions, and there’s also an installation video you can follow.
If you encounter any problem, iSPring’s customer support will prove to be very helpful. Just give them a call, and they’ll guide you.
Note: If you don’t have enough space under your sink to install the iSpring RCC7AK, you can set it up in the basement. But make sure it’s not too far away from the sink (ideally no more than 10 ft.) to avoid a huge pressure drop.
You’ll need to replace the filters a bit more frequently than with other RO systems. The short filter life is not that surprising considering the price point.
The three pre-filters and the remineralization filter last on average 3-6 months, depending on your home’s water quality.
It is essential that you change the pre-filters on time to prevent degradation of the RO membrane.
We recommend using a TDS meter to monitor water quality. When TDS levels start to rise (take a reading once a month), replace the filters.
The carbon post-filter needs to be replaced annually while the RO membrane is good for 2-3 years.
iSpring sells a convenient 1-year filter replacement set that consists of 6 pre-filters (2 of each), two remineralization filters and one post-filter.
You can also buy a 2 or 3-year replacement set. Both come with a replacement RO membrane.
Replacing the filters is an easy DIY job. It takes about 10-20 minutes.
What We Like the Most About the iSpring RCC7AK Reverse Osmosis Water Filter
What We Don’t Like
The iSpring RCC7AK Is Perfect For You If...
You are looking for an affordable reverse osmosis water filter that is just as good as pricier systems and produces mineral water.
Our Bottom Line
The iSpring RCC7AK is a great bargain.
It does not feel as robust as pricier RO filters, and the filter life could be longer. But where it matters most, filtration performance, it’s just as good as any other RO filter.
The 6-stage filtration system guarantees safe and healthy drinking water that also tastes great.