Why Remineralizing RO Water Is Necessary?


My friend suggested me to buy remineralizing RO filter as he read in [various guides](https://www.aquaprofessor.com/how-to-remineralize-reverse-osmosis-water/) that such filters are necessary. But I thought RO filters are enough for safe water. Helpful answers are welcome!

In: 1

What country are you in. Many countries have drinking water that doesn’t need to be filtered, and therefore you original premise may be wrong.

It’s safe to drink yes, but you are missing mineral for yourself and health. You can supplement it, but why?

With regular drinking water you get to consume some metal ions for free, calcium, magnesium, iron from rusted pipes. Otherwise these have to come from food, cooked on a rusted iron pan. A slightly mineralized water might taste better compared to distilled. It is probably not a big deal. I’ve heard people can taste the difference in coffee and cooked pasta, but I’ve not been able to.

And if you have to buy an additional filter part, then the minerals are no longer free.

Have you ever tasted distilled water? It tastes horrible and flat. Certain levels of minerals are needed for water to taste good.

It’s not about safety.

There’s not too much research that have evaluated if drinking RO water poses a big threat to human health, but there are some theoretical reasons why it might be a bad idea to drink a significant amount of it. Certainly if you were a fish and had to live in the water, it would be lethal, but assuming you are a human eating table salt and getting most of your minerals from food you may not be severely impacted.

Your body is basically a soup of a lot of salts and minerals.
Most normal fresh water contains these in amounts that we are adapted to consuming, and you are able to control your internal mineral levels relative to these.

RO water has nothing in it. Because diffusion works down a concentration gradient – i.e. on average, stuff will always move from a high concentration to a low concentration until it evens out – this might pose a problem for our mineral soup bodies. It is so pure that minerals might diffuse out of our bodies and into our RO filled digestive tract.

Also, while mineral are at a very low concentration in the RO water, the water molecules are not? If you cut two slices of a courgette/zucchini or similar vegetable and sprinkle some salt on one of them, you’ll notice big beads of liquid forming where the salt was touching it. The salt is drawing the water out of the vegetable and towards the salt. In this scenario, your salty blood is the salt and the courgette is your stomach full of RO water.
The salts in your body could draw in too much RO water and throw off the balance of salt and the volume of water in your blood, causing all sorts of problems and also hypertension (high blood pressure) from too much blood volume.

These are largely theoretical issues with RO water, and haven’t been well evaluated in studies. Some people seem to drink pure RO water frequently with no apparent side effects.
It’s likely that consuming RO water in small amounts infrequently is probably not too damaging if you’re in good health and not lacking any minerals. In the short term it’s definitely better than drinking contaminated water. That said, there’s enough logic behind the concerns that I would avoid drinking it if I could.