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Every day people ask me: Is reverse osmosis water unhealthy?

I’ve written this short article to answer your questions. The entire premise of my work is that you cannot know what water filter or water purification system to use without first knowing what contaminants are present in your water. It is the contaminants and the technology required to remove them that determine what water filter you need. Period.

Some contaminants can only be removed by the technology of reverse osmosis. These include high total dissolved solids, nitrates, radioactive metals, and many other metals. Drinking water containing these contaminants is dangerous to your health and longevity.

When I recommend reverse osmosis because of these contaminants people inevitably ask me the following:

“But I hear that reverse osmosis strips the water of everything, including healthy minerals…”

Yes it does, but the presence of cancer causing contaminants can kill you, whereas minerals can be obtained from food. I personally supplement magnesium to be sure I'm getting enough.

“Doesn’t reverse osmosis waste a lot of water?”

RO does use water to carry the contaminants down the drain. I refer to this as process water. It is necessary to provide pure water for drinking and I do not view it as wasted.

“Isn’t reverse osmosis water unhealthy to drink?”

Reverse osmosis water is fine to drink. I do modify the output water in the RO systems I sell to make the water slightly alkaline. I think this is healthier than normal RO water. And if there is a downside to water produced by reverse osmosis it would be the acidity of the water. So, again, I counteract this by adding a filter to raise pH.

There are several studies produced by the World Health Organization which purport to correlate low tds (ie: low mineral content) water to higher rates of Cardiovascular disease (CVD). I have read each of these papers and others in an attempt to learn about this correlation. It seems that the studies are broad and water is only one of many factors which may be related to CVD. The paper concludes that there is no definitive correlation and yet there is circumstantial evidence that warrants further study.

While the primary study which cites low tds water as a problem appears legitimate there is strong contradictory evidence that has never been considered. I’ll discuss this again below.

When you drink the water produced by the RO system I sell your water will be similar to that of Seattle, Portland, San Francisco, and Denver – fresh mountain runoff from snow melt. The tds (mineral content) of my RO is about 30 ppm.

Here are U.S. cities with comparable tds:

Seattle: 34 – 47 ppm

Portland: 23 ppm

San Francisco: 27 – 154*

Denver: 39 – 216*

* the lows above would be snow melt during winter months and the higher numbers would be rain runoff during summer and fall.

If RO water were unhealthy to drink then the populations of these major cities would be experiencing those same health problems. But in fact the people in these cities are healthier than the rest of the United States;

Rates of CVD in Portland:

Rates of CVD in Seattle:

CD-HRT2013.pdf ( - Seattle rates are lower than the rest of the state

Rates of CVD in San Francisco:

Rates of CVD in Denver:

What’s apparent from all of these studies is that rates of CVD deaths have more to do with diet, tobacco use, exercise and other factors not related to water.

“Do I have to add healthy minerals into the water?”

No. You don’t. But if you decide to do so the only time of day I think this would matter is the first glass of water you drink each morning. After that your food will provide minerals. Drinking one or two glasses of appropriately filtered and slightly chilled water first thing upon rising is one of the most effective actions you can take for your health.

Is reverse osmosis water unhealthy? Nothing anywhere in the literature suggests that it is except for a series of WHO articles which fail to take other factors into account. I do think that raising the pH by adding calcite is a useful thing to do.

One huge problem with adding minerals to water is that NONE of the mineral additives on the market today provide the optimum blend of minerals as identified in the WHO report. That reports suggests the following as optimum:

tds: minimum of 100 up to 200 – 300 ppm, with

calcium: 20 – 30 ppm

magnesium: 10 ppm

bicarbonate: greater than 30 ppm

pH: 7.5 *

* unlike the many claims by the manufacturers of alkaline ionizers pH was not related to health. The presence of other minerals were not related to health effects but trace levels of sodium and potassium as electrolytes would be beneficial.

You can try adding mineral drops to your water but doing this won’t give you any kind of ideal mix of minerals.

Remineralizing Filters

I also have to add that the many companies selling filters that supposedly add minerals back into your water, at least at this point in time, are pulling your leg. They sell you an expensive mineral cartridge but it does not add minerals to the water. I’ve tested them. The water moves through the filter too quickly to dissolve the minerals in the cartridge so they just do not work.

They do raise the pH and alkalinity but in my opinion they raise both too much. I prefer the cartridge that I use which raises pH to about 7.4 and the alkalinity to about 20 ppm. By giving the aggressive RO water something to carry, in the form of alkalinity, the aggressiveness is eliminated.

I will say that in an ideal world the water you drink would contain low levels of minerals, in the range between 30 to 250 parts per million. More than 250 ppm is too much and high mineral content will make the water less hydrating.

“Is reverse osmosis water dead?”

Really? And just where do these rumors get started? No. Energetic testing by customers of mine have shown that water had more energy after passing through the RO system I sell than coming straight from the source. But maybe that’s due to the enhancements I add to the systems I sell.


Is reverse osmosis water unhealthy? I do think that drinking water with a low level of minerals is better than drinking water with no minerals at all. But this is counteracted by drinking water with contaminants. So you decide.

I sell the most effective RO system in the marketplace and you can see my kitchen water filters here.

Someone wrote to me and asked why I titled this article ‘The Dangers of Reverse Osmosis’. I did so because there is so much bad information on the internet that does indicate, wrongly, that drinking reverse osmosis water is dangerous to your health.

Consider this: I research this topic more than you do. I research it more than any of the various health writers who speak poorly of reverse osmosis drinking water. I have researched alkaline water and its alleged benefits. I’ve read all of the English language papers on the topic even those produced by WHO. And if I ever learn anything new I share it with you, my readers.

In all humility I must ask you to believe me when I say that I write what I think is true and factual. If I ever learn of anything that runs counter to the information provided herein I will share it with people who subscribe to my email lists. I am researching the issue as I write this. In the meantime I urge you to ignore the charlatans who write about water but know absolutely nothing about it.

yours in health,

Jim McMahon revised 5-18-23



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