What can be Removed with Reverse Osmosis System?

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A Reverse osmosis system helps to purify drinking water. It is one of the best water purification methods and can remove up to 98% water contaminants.

RO systems remove common contaminants from the water, including heavy metals, mineral ions such as magnesium and calcium. It can also remove nitrates, pesticides, fluoride, sulfates, bacteria, arsenic, and more.

The units are usually installed under the sink in your kitchen or basement to ensure that you have a constant supply and access to pure water.

In this post, we’ll help you discover the contaminants that RO systems remove and what they can’t. Keep reading.

Water Contaminants that RO systems Remove

Calcium and Magnesium

What can be Removed with Reverse Osmosis System

Although calcium and magnesium are essential minerals for good health, a high concentration of these minerals in the water causes water hardness. The minerals also cause scale build up which can block your plumbing.

If living in a locality with hard water, these minerals end up in your plumbing pipes. They cause build up that can damage not only the pipes but also any connected appliance.

Reverse osmosis helps to fix this up by filtering the minerals out. To keep the system functioning properly, all you need to do is replace the filters regularly.


Metalloids are chemicals that are neither non-metal nor metal. They include arsenic, boron, and silicon. You might have heard about arsenic, right? It’s the most popular metalloid and is considered a toxic water pollutant.

Arsenic gets into the water from natural erosion and is especially high in groundwater. If your household uses well water, you need to invest in an RO system to help you remove it.

A reverse osmosis system removes arsenic and any other metalloid by pushing the water through the semi-permeable membrane.

Lead and Copper

An RO system will help you get rid of lead and copper present in your drinking water. So, where do these contaminants come from?

According to the (EPA), a US Environmental Protection Agency, the main source of lead and copper in our drinking water is corrosion of household plumbing.

This means that your water pipes could be adding metals to your water without your knowledge.


Chlorine could be the reason why your tap water smells and tastes bad.

But do you know that not every reverse osmosis system can remove chlorine from the water? This is because some of these systems don’t come with the right carbon filter to remove chlorine effectively.

Only RO systems with the National Sanitation Foundation Certification 42(NSF-42) can remove chlorine. Therefore, before purchasing the unit, check to ensure that it comes with this certification if you intend to use it for chlorine removal.


Fluoride is usually added to your drinking water by water treatment plants. It is usually added to the water to strengthen the teeth, reduce cavities and tooth decay.

Fluoride ions get removed from the water as it flows through the RO system. And although it’s never possible to remove 100%, most of the fluoride is successfully removed.


The presence of parasites in your drinking water is very dangerous; you can get very sick should you ingest them. Giardia and Cryptosporidium are some of the common parasites that can live in your water.

RO systems remove parasites through the semi-permeable membrane, but it has to be clean at all times to ensure that it does its job well.

When replacing the filters, ensure that you have gloves on since these parasites can attach to the semi-permeable membrane.


RO systems are highly effective in removing viruses. Remember, viruses can survive in water for a long time hence a major problem.

Some of the viruses that reverse osmosis remove include hepatitis A, norovirus, enteric, and rotavirus.

Pesticides and Herbicides

Although RO systems are highly efficient and effective at removing most water contaminants, not all work the same. In fact, some remove a very low percentage of these contaminants from the water.

To ensure that you get the best, be on the lookout for a unit that comes with a semi-permeable membrane made of a thin film. It’s the only one that can get the work done, most to perfection.

And how will you know that a system has a membrane made from a thin film composite? Check the packaging go for one labeled as either NS-100, FT-30, or DSI.

Total Dissolved Solids(TDS)

Total dissolved solids are contaminants in your water that are dissolved.RO systems can remove 90% to 95% of TDS in your water.


Sediment is any type of particle visible to the human eye. It’s often things like mud, silt, sand, and dirt.

The pre-sediment filter on an RO system removes the sediment from the water before it reaches the semi-permeable membrane and carbon filter.


It’s impossible to tell that there’s nitrate in your tap water since it’s odorless, colorless, and tasteless. It can get into your water supply from agriculture, septic systems, or industrial areas.

While RO systems can remove nitrate, don’t try carbon filters or water softeners because they can remove nitrate from your water. Also, don’t try boiling the water, as this will only increase nitrate concentration.


Although Reverse Osmosis can remove almost every type of water contaminant, it can’t remove all bacteria.

Actually, it isn’t only RO; there isn’t a single known filter that can remove all bacteria from drinking water.

What Can’t be Removed by Reverse Osmosis?

Since some contaminants are molecularly smaller than water, some RO systems cannot remove them from tap water. They include:

Carbon Dioxide

RO systems can’t remove carbon dioxide because it’s a gaseous component. Gases slip through the semi-permeable membrane unhindered, unlike other contaminants.

However, the best thing is that carbon dioxide is harmless and won’t affect the taste or smell of your water.


Radon is a radioactive element, but while RO systems can remove other radioactive elements, they cannot remove radon from tap water.

This is because radon is a colorless, tasteless, odorless radioactive gas and, as aforementioned, reverse osmosis can’t remove gases.

Which RO System is the Best for You?

There are lots of RO systems in the market today, a situation that might make it a little harder for you to get the right one for your home. Some popular solutions that you can consider include:

1. iSpring RCC7AK – Best Under Sink RO with Alkaline Remineralization, Price on Amazon

iSpring RCC7AK is exclusively designed to help restore the natural alkalinity and mineral water balance. It is a reliable RO system that converts your tap water into clean, pure, and healthy water by removing 99% of harmful contaminants.

The system includes an alkaline remineralization filter, which restores healthy minerals to give your water a natural taste.

It features a beautiful European-style faucet and a transparent first stage housing for visual inspection. It has 3 extra-long pre-filters that remove large contaminants, an ultra-fine RO filter to remove tiny contaminants, and a GAC filter to provide final polishing of the purified water.

2. iSpring RO500 – Best tankless reverse osmosis system for well water, Price on Amazon

This tankless RO system will fit you well if your household uses well water. It offers superb filtration performance thanks to the 3 in 1composite sediment and carbon block filter (1st stage), 2nd stage RO membrane, and a 3rd stage carbon block filter that enhances the taste of your water.

RO500 removes up to 99% of water contaminants, including lead, fluoride, arsenic, asbestos, sodium, calcium, and more. It also has a fast flow rate of 500 GP and pure water to wastewater ratio of 2:1.

The unit features smart features like real-time TDS and a smart faucet to enhance your user experience. It’s also easy to install.

3. AquaTru 4-Stage Countertop RO System, Price on Amazon

AquaTru’s patented RO system removes toxins, microplastics, hormones, arsenic, carcinogens, lead, chromium, among other toxins from tap water, bottled, and filtered water.

It is designed to remove 1000’s of contaminants from your tap water, is easy to use, and comes in a compact design.

The system requires no installation; hence easy to set up. It is also cost-effective and environmentally friendly. It requires filter change every 6 months to 2 years.

4. APEC Water Systems RO-CTOP RO System, Portable Countertop, Price on Amazon

If interested in a portable RO system, try out APEC RO-CTOP. It is a high-performance 4-stage system that provides clean, pure, and tasty water.

It hooks up to most standard faucets in minutes, is lightweight for easy packing and transport, and is easy to install.

The 90 GPD portable system comes with high capacity 10-inch filters that provide reliable and long-lasting performance. It is perfect for condos, apartments, motor homes, students, and travelers.

One thing to note about this system is that it’s not compatible with sprayer faucets, pull-out faucets, and special-size designer faucets.


Reverse osmosis removes a great number of water contaminants from the water, hence one of the best water filtration and purification systems you can find around. Thanks to this system, you are assured that your water is clean, safe, and healthy for drinking.

Should you decide to get an RO system for your home, you’ll have made the best decision.