Osmosis water: healthy or unhealthy?

Reading time: ~11 minutes

"Osmosis water is the purest water there is." You'll read that sentence on almost every webshop selling an osmosis device. And technically, it's true: reverse osmosis removes up to 99% of dissolved solids from your water. But pure doesn't automatically mean healthy, because along with the contaminants, the minerals that give water its taste and nutritional value also disappear.

The question "is osmosis water healthy or unhealthy?" is therefore increasingly common. In this guide, we provide an honest answer based on authoritative sources, explain why osmosis water feels tasteless, and show what alternative purifies without discarding healthy minerals.

1. What exactly is osmosis water?

An osmosis device usually consists of several steps: a pre-filter for particles and chlorine, the RO membrane as the heart of the system, and sometimes a post-rinse. The membrane is so fine that even dissolved salts cannot pass through it. This makes osmosis the most drastic filtering method available for home use, even more drastic than a reverse osmosis water filter itself might suggest.

Important to know: osmosis water is not the same as distilled water. Distillation involves boiling water and collecting the steam; in osmosis, the separation occurs purely mechanically through pressure. Both produce demineralized water, but through entirely different processes.

2. Is osmosis water healthy or unhealthy?

The honest answer: osmosis water is not unhealthy or dangerous to drink, but it is also not the ideal drinking water for daily use. For a healthy adult who eats a varied diet, occasional osmosis water is not a problem, as your body gets most minerals from food, not from water.

The nuance lies in long-term, exclusive use. The World Health Organization concluded in its report on nutrients in drinking water that demineralized water is not ideal as drinking water. Those who drink only demineralized water for extended periods excrete on average more calcium, magnesium, potassium, and sodium through urine. The WHO therefore advises remineralizing demineralized water before it is used as drinking water.

It is important to emphasize: this is no reason to be alarmist about tap water. Dutch tap water is excellent, is more strictly controlled than foodstuffs according to Vewin, and meets quality standards in 99.9% of measurements. Osmosis is therefore rarely necessary to make your tap water "safe". The real question is whether you want to retain the minerals, and that is precisely where osmosis falls short.

3. Why osmosis water contains no minerals

The RO membrane does not distinguish between "bad" substances and "good" minerals. According to the WHO, reverse osmosis removes 92 to 99% of dissolved minerals, including calcium and magnesium. Everything dissolved is removed, whether it's lead or a healthy mineral.

And these minerals do matter. Calcium and magnesium are necessary, among other things, for bone formation, nerve impulse transmission, and muscle contraction, such as the heart muscle. Food is the main source, but drinking water provides approximately 6 to 8% of your daily calcium and magnesium intake, according to research commissioned by RIVM. In the Netherlands, it is recommended that drinking water contain between 20 and 60 mg of calcium and between 10 and 30 mg of magnesium per liter. Osmosis water is far below that, often close to zero.

This is also why osmosis water is often perceived as "flat" or "tasteless." The fresh, full taste of good water comes precisely from those dissolved minerals.

4. Benefits of reverse osmosis

Osmosis certainly has its strong points. To be fair:

• Very thorough purification: RO removes up to 99% of heavy metals, PFAS, nitrate, drug residues, and microplastics. If it's purely about removal, osmosis is one of the most powerful methods.
• Limescale-free water: because calcium is also removed, osmosis water is completely limescale-free. Useful for applications where limescale is a problem.
• Ideal for specific applications: for aquariums, streak-free window cleaning, irons, and some laboratory applications, mineral-free water is desirable.
• Consistent quality: regardless of the composition of your tap water, osmosis delivers a fixed, predictable end result.

These advantages explain why "osmosis water" is often searched for in relation to cleaning, aquariums, and appliances. For those purposes, it is excellent. For daily drinking water, it is more nuanced.

5. Disadvantages and considerations

Against the thorough purification, there are a few real disadvantages, especially if you want to use osmosis water as daily drinking water:

• No minerals: as described above, calcium, magnesium, and potassium disappear. For daily drinking water, the WHO recommends remineralization.
• Flat taste: many people experience osmosis water as "dead" or tasteless, precisely because the flavor-giving minerals are absent.
• Water wastage: a classic osmosis device flushes some of the water as wastewater to keep the membrane clean. Depending on the system, several liters of tap water are lost per liter of drinking water.
• Installation and maintenance: an osmosis device is typically larger, requires periodic membrane maintenance, and sometimes a separate tap or tank under the counter.
• Cost per liter: buying loose osmosis water from a supplier quickly costs several tens of cents per liter, comparable to, or more expensive than, an efficient home filter system.

In short: osmosis solves a problem that Dutch tap water often doesn't have (unsafety) and creates a new one (mineral loss). For those primarily concerned about PFAS, lead, or medicinal residues, there is a middle ground that purifies without stripping everything bare.

6. Osmosis water vs. filtered mineral water

How does osmosis water compare to the alternatives? This table sets out the main options.

The table shows the pattern: osmosis is the only option that removes both contaminants and minerals. All other options retain minerals but filter less thoroughly, except for the water filter that purifies and mineralizes, which combines the best of both worlds.

7. Who is osmosis water suitable or not suitable for?

Osmosis water is fine for:

• Aquariums: many aquarium owners use osmosis water to build up water values themselves, with a controlled ratio of minerals.
• Washing windows and glass: mineral-free water dries streak-free, which is why window cleaners often work with osmosis water.
• Appliances: irons, steam cleaners, and humidifiers benefit from limescale-free water.

For daily drinking water, there is a better choice:

For drinking at home, you want pure and mineral-rich water. At PureFilter, we see that customers who previously had an RO system switch precisely because they felt they were drinking "dead water": well-filtered, but without the dissolved minerals that give water its fresh taste. A home water filter that mineralizes solves this without the disadvantages of osmosis. If you are in doubt between options, feel free to compare tap water versus bottled water or read why Dutch tap water is generally healthy.

8. The alternative: purifying without losing minerals

The PureFilter Mineral+ is designed to solve exactly the problem of osmosis. It is a compact under-counter filter that removes more than 100 contaminants, including PFAS, microplastics, heavy metals, chlorine, nitrate, and drug residues, up to approximately 99%. But instead of leaving the water stripped bare afterward, the unique Swedish Mineral Rock™ technology adds calcium, magnesium, and potassium back in.

The result is water that is fresher, softer, and richer in minerals: the best of osmosis (thorough purification) without the biggest disadvantage (mineral loss and flat taste). And because it is NSF-certified (NSF 42, 53, 61, and 372), its purifying effect has been independently tested.

9. Frequently asked questions about osmosis water

10. Conclusion

Is osmosis water healthy or unhealthy? It is safe to drink, but not ideal as daily drinking water. Osmosis removes up to 99% of contaminants, but simultaneously strips the healthy minerals calcium, magnesium, and potassium, and it is precisely these that give water its taste and nutritional value. The WHO therefore recommends remineralizing mineral-poor water.

For aquariums, window washing, and appliances, osmosis water is excellent. But for the glass of water you drink every day, a filter that purifies and mineralizes is the smarter choice. The PureFilter Mineral+ removes more than 100 contaminants and adds minerals back via Swedish Mineral Rock™, NSF-certified, installed in 5 to 10 minutes.

Want to know more? Check out our explanation of the reverse osmosis water filter, the under-sink water filter, or ask your question via our frequently asked questions.