Is Reverse Osmosis Water Bad for You?

If you’ve been looking at water filtration solutions for your home, you’ll know that reverse osmosis is one of the most popular options.

Typically, reverse osmosis filters are installed in a point-of-use location: beneath your kitchen sink. This gives you immediate access to water that has been filtered by a reverse osmosis system from your faucet.

There’s no denying that reverse osmosis systems are incredibly good at what they do – but what if they’re too good? You may have read the recent World Health Organization report that expressed concern around drinking RO water, accompanied by several damning studies, that probably only intensified your own concern.

So, does drinking reverse osmosis water have the potential to do more harm to your health or diet than good? You’ll find all the answers you’re looking for in this guide.

What is Reverse Osmosis Water?

Reverse osmosis water is drinking water that has been filtered in a reverse osmosis system.

This type of water filter consists of several filters: a sediment pre-filter, an activated carbon filter, and a post-filter. Between the AC filter and the post-filter is a semi-permeable membrane, which is responsible for removing the good majority of contaminants from drinking water.

During the reverse osmosis process, water is forced at a high pressure through each filter stage – which greatly reduces sediment, environmental impurities, chlorine and lead – before entering the RO chamber. Hitting the RO membrane with such a strong force means that only the water particles, which are small enough to fit through the membrane, are able to pass through.

The contaminants, on the other hand, which are all larger than the membrane’s 0.0001-micron pores, are too large to pass through, and bounce back into the RO chamber. These contaminants are then sent down the drain along with some water waste.

The water that leaves the RO system is, thanks to this intensive process, clean to the point of being pure.

what is reverse osmosis water

What Does Reverse Osmosis Remove from Water?

Reverse osmosis removes more than 99.9% of all TDS (total dissolved solids) from drinking water.

This includes contaminants such as:

It’s actually easier to say what reverse osmosis systems can’t reduce or remove – they may struggle to fully eliminate agricultural chemicals that leach into the environment like pesticides and herbicides, certain dissolved gases, and some particularly small microorganisms, like viruses.

You can see that the effectiveness of reverse osmosis systems is actually to their detriment as well as their benefit. They may remove traces of harmful impurities, but they also reduce or remove healthy minerals and salts that are found in American alkaline water sources.

Related: Does reverse osmosis make water acidic?

Benefits of RO Water

There’s no denying the advantages of drinking reverse osmosis water, particularly when it comes to your health. Some of the best benefits of RO water include the following:

Water is Guaranteed Safe to Drink

Even modern tap water supplies are laced with contaminants that may be harmful or toxic to our bodies when consumed in the smallest amounts, such as lead. A reverse osmosis system can provide water that’s completely safe to drink, with these dangerous contaminants filtered out during the RO process.

Save Money on Bottled Water

Does your family rely on plastic water bottles to get by? If you currently don’t drink from your home’s kitchen faucet, whether because it smells bad or because it’s contaminated with dangerous pollutants, you’re probably spending a few hundred extra dollars per month on bottled water just to stay hydrated.

One of the best benefits of buying a reverse osmosis water filter for drinking purposes is that you won’t need to factor in for buying commercial water bottles ever again. This could save you hundreds, maybe even thousands, of dollars on a yearly basis – plus, you’re doing your bit for the environment.

Reduces Sodium from Softened Water

A reverse osmosis system at your kitchen sink can mitigate the adverse effects of a whole-house softening system. Yes, it’s a fact that your home’s plumbing, pipes, faucets and fixtures can benefit hugely from salt-softened water, especially if you’re dealing with a serious hard water issue, but if you don’t want to drink water with an added sodium content, I would really recommend buying a reverse osmosis system, which can easily eliminate that sodium before the water reaches your faucet.

Better Cooking Option

Reverse osmosis water isn’t only healthier for cooking with – it’ll also give your foods a better taste. Preparing foods to eat with water containing iron, sulfur or chlorine sometimes may cause the taste of foods to change or worsen, particularly if you’re boiling foods in this water. Pure water can really make a huge difference when you’re making soups, boiling pasta or whipping up a batch of homemade bread.

Disadvantages of Reverse Osmosis

As with any water treatment option, reverse osmosis water filters do have their disadvantages. Let’s take a look at some of the setbacks of consuming reverse osmosis water.

Healthy Minerals Removed

As I mentioned briefly earlier, reverse osmosis filters are so good at what they do that they remove everything from a standard glass of tap water – and, in fact, that includes the good stuff. We know from research that vitamins and minerals like calcium and magnesium are essential nutrients for the health of the human body, and are needed for strengthening teeth and bones, improving the body’s ability to regulate blood pressure and much more.

Demineralized water contains a lack of these particular vitamins and minerals, and has the potential to impact your health and cause concerns linked to your metabolism of kidney function if you don’t get your nutrition from an alternative source.

Expensive purchase & maintenance

It’s not a disadvantage of reverse osmosis water itself, but the system that produces it: RO water systems are costly to purchase and maintain. You’ll need to ensure that each stage of the filtration system is working at its optimum, which means replacing the filters when required. Typically, filters need changing once every 6-12 months, while the RO membrane needs replacing every 2 years.

“Flat” Taste

While reverse osmosis water is safe to drink, some people don’t enjoy its taste. Alkaline water tends to taste better because it contains certain minerals and vitamins that increase its pH. Fresh water from an RO system, on the other hand, has had these essential elements removed in the filtration process, which will give it a related “flat”, unappealing taste.

Wasted Water

To benefit from a high level of clean, purified water for drinking, you’ll have to accept that the RO method of water filtration does waste water in the process. This is an unavoidable aspect of producing pure water using the RO filtration process – no amount of research or testing has determined a suitable answer to this problem.

There has to be a way to drain away the unwanted contaminants, and the easiest and most highly beneficial solution is to install a drain to wash them away with water. While it won’t add a noticeable cost onto your water bill, the wasted water may still be a turn-off to you.

Remineralizing RO Water

While reverse osmosis water is considered safe drinking water, and you can get all the minerals that the RO process removes by following a well-rounded diet, you may still want to remineralize your RO water for the sake of your health or drinking enjoyment. For instance, if you think that you’ll drink less in the long term if it tastes less appealing, it makes sense from a health perspective to make mineralized water for your hydration.

Many RO systems come with an included remineralization filter, which is the easiest solution for reintroducing healthy minerals. If your filtration system didn’t come with a remineralization filter, you may be able to buy an additional filter to install at your waterline that re-adds minerals after the RO water system.

Another option would be to introduce minerals manually with mineral drops, which are available in health stores or online. Instructions vary depending on the manufacturer, but it’s not a difficult task. Most mineral drops are concentrated, and a couple of drops in a single pitcher is enough.

Remember, this is only a necessary option for improving the taste of your tap water, as the minerals removed by reverse osmosis won’t leave a huge hole in your dietary intake. In fact, the nutrients we get from unfiltered tap water are so minimal that your body wouldn’t suffer an impact, health-wise, if you drank reverse osmosis water for the rest of your life. Just make sure you’re getting plenty of nutrients from primary mineral-rich natural food sources in your personal diet, which is naturally higher in the likes of calcium and magnesium anyway.

Alternatives to Reverse Osmosis

You don’t have to go with reverse osmosis filtration systems if there’s something about RO that puts you off. There are a number of similar filters that offer the similar results, using slightly different processes to get there.

Carbon Filtration

Carbon filtration is a great whole-house or portable filtration option if you’re looking for something a little less thorough than a reverse osmosis unit that still tackles the essential compounds.

Namely, carbon filtration can get rid of the bad-for-you chemicals like chlorine, as well as metals that have damaging health effects, such as lead. Experts recommend this type of filtration for dealing with common municipal water issues, as they’re best for removing low levels of impurities from your tap. However, these filters can’t deal with the breadth of issues that RO can, which means that low levels of substances like fluoride may remain.

KDF Filtration

KDF stands for kinetic degradation fluxion. This type of media is made from granules of purity copper-zinc that stimulate a redox reaction – either oxidation or reduction – to greatly reduce unwanted particles. During KDF filtration, these particles and converted into harmless substances that are eliminated when the system performs a backwash.

The chemical reaction produced by KDF redox provides the answer to problem sources of contamination like heavy metals, hydrogen sulfide and chlorine. This process is certified to NSF Standard 61, and also meets EPA and FDA standards for copper/zinc content. While it isn’t as highly effective as reverse osmosis, again, KDF filtration can still tackle the most common contamination issues faced by most American homes.


Ultrafiltration is very similar to reverse osmosis when it comes to water quality. In the ultrafiltration process, water is sent at a high pressure through a semi-permeable membrane, removing nearly all harmful compounds. This type of system can siphon out plastic particles, harmful chemicals, silt, fluoride, metals, proteins, and bacteria, as well as hundreds of other bad-for-you toxins that can pose a health risk on consumption.

So what makes ultrafiltration different from reverse osmosis? Typically, ultrafiltration membranes have slightly larger pore sizes, so they’re not as effective in eliminating very small pollutants, like bacteria.


Finally, to achieve a similar result to reverse osmosis, you could use a distiller to produce distilled water. The benefit of a distiller is that it’s a smaller upfront cost, and it costs virtually nothing to maintain.

Distilled water is just as healthy as RO water, as distillation boils water until it evaporates and condenses, leaving 99.9% of all TDS in the boiling chamber, where they can be washed away. Distillation can take up to 4 hours to produce a single gallon of water, though, so it may not be the best choice for your whole family.

So, Is Reverse Osmosis Water Bad for You?

If you’ve read the WHO’s all-round negative public report on the reasons to reconsider drinking water produced by RO purification, you’re probably especially concerned about whether RO water may pose a problem to you. But while it’s certainly important to consider the case made by the experts, provided you drink fresh RO water that has had no time to potentially accumulate toxins, and you accompany your hydration habits with a healthy diet, you have nothing to worry about.

I would suggest that you ensure you’re aware of the problems highlighted around the WHO’s medical studies, but side-effects of RO water including reduced hydration and a reduction in mineral intake can be treated with mindfulness. In short, the biggest associated concerns, according to a professional or scientific perspective, are usually linked to the fact that the American diet simply doesn’t contain the nutrients we need to consume to survive. That’s where the deficiency issue ultimately stems from, from one state to the next.

Make sure that you’re drinking enough by using a two-liter water bottle and ensuring you empty it by the end of the day. And provided you’re getting a high level of vitamins and minerals in the foods you eat, there’s no cause for concern.

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