Does Reverse Osmosis Remove Magnesium from Water?
Written by: Gene Fitzgerald // Last Updated: Sep 8, 2023
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The effectiveness of reverse osmosis makes it a prime choice for filtering water for household use.
And while it’s known that reverse osmosis deals very well with many kinds of water impurities and contaminants, how good is it when it comes to magnesium specifically?
Let’s explore.
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Key Takeaways
- Yes, reverse osmosis removes magnesium from water very effectively. Reduction rates of 97% can be achieved.
Does Reverse Osmosis Remove Magnesium from Water?
So, does reverse osmosis remove magnesium from water?
Yes, reverse osmosis removes magnesium from water. In fact, it’s one of the most effective methods for filtering magnesium out of water.
How Much Magnesium Does Reverse Osmosis Remove?
As much as 97% of the magnesium present in your water will get removed by reverse osmosis filtration. This figure will vary slightly according to factors like the overall contamination levels of the water, but it should be pretty close to reality in most cases.
How Does Reverse Osmosis Remove Magnesium?
Reverse osmosis works by forcing water through a thin, semipermeable membrane using high pressure. The tiny pores of the membrane only allow water molecules to pass through, rejecting everything else which gets mixed with the wastewater stream and sent away.
This process is highly effective against various impurities, including magnesium. There’s nothing special about the way magnesium gets filtered out by reverse osmosis systems compared to other contaminants. Its particles are large enough to get blocked by the pores on the membrane, and that’s all that matters.
Further Reading:
Other Minerals Removed By Reverse Osmosis
It’s not just about magnesium though. Reverse osmosis is a very thorough method for filtering water in general, and it can effectively remove pretty much any minerals.
Calcium
Calcium is the most common mineral in the human body, and it’s also often found in water supplies. Reverse osmosis can remove calcium with an effectiveness of over 96%. In some cases, it can reach more than 98% if the conditions are right.
Potassium
Potassium is another commonly occurring mineral, found in many foods and also in water sources. Reverse osmosis removes at least 92% of the potassium present in unfiltered water.
Sodium
Sodium is also frequently found in water supplies, and it’s abundant throughout the Earth in general. Reverse osmosis is very good at removing sodium, reducing its concentration by 92% to 98%.
Copper
Copper commonly finds its way into water supplies through old pipes, but it’s also naturally present to some extent. With reverse osmosis, you can remove as much as 97-99% of the copper found in your water.
Zinc
Zinc is similar to magnesium in some aspects, although it’s far from being as common. Zinc is removed with an effectiveness of 98% – 99% by reverse osmosis systems.
Fluoride
Fluoride is something else that many people are interested in removing from their water, even though it also has some health benefits when used in certain amounts. Fluoride may be specifically added to your water supply by your water company. This is done in many parts of the world in an attempt to improve dental health, although it’s a controversial approach. In any case, reverse osmosis removes 94% – 96% of fluoride present in water.
Phosphorus
Finally, soluble phosphate is reduced by as much as 95% – 99% by reverse osmosis. It’s good to have phosphorus in your water to some extent if you’re using it for agricultural purposes, but it’s easy to go over the recommended line, so it’s better to treat your water.
The Problem with Reverse Osmosis and Mineral-Laden Water
With all of this being said, reverse osmosis membranes are very delicate and prone to clogging when used on mineral-laden water. As such, you need to be careful if you want to avoid your RO membrane from clogging rapidly. Essentially, if you are dealing with excessive levels of magnesium and other hardness ions, it’s better to use a water softener for removal.
Should You Remineralize RO Water Before Drinking?
One of the main benefits of reverse osmosis water can also be seen as one of its main drawbacks, depending on the perspective. Reverse osmosis is very thorough at purifying water. It removes practically all contaminants, leaving behind nothing but pure, clean water.
This is normally great if you’re concerned about drinking contaminated water, but you must also be careful. Water naturally contains various minerals in certain amounts, including the ones we listed above. Consuming those in small quantities can be beneficial to your health. That’s why it’s recommended to remineralize your reverse osmosis water before drinking it. Here are some guidelines for how much to add:
- Magnesium – between 10 mg/L and 30 mg/L
- Calcium – between 20 mg/L and 60 mg/L
If you have any thoughts about the question, does reverse osmosis remove magnesium, please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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