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Small-Scale Question Sunday for July 26, 2026

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

Culture war topics are accepted, and proposals for a better intro post are appreciated.

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Can anyone comment on the dangers of drinking low total dissolved solids (TDS) reverse osmosis water on general health, especially with a baby in the home? I recently installed a reverse osmosis filter and then discovered that low TDS water can potentially be dangerous because of a lack of minerals like calcium, magnesium, and phosphate. My RO filter doesn't have a remineralization add-on.

One reverse osmosis study from India

Assume that me and my baby otherwise have the very best foods and baby formula available. Some random reddit comments indicate that eating a high quality diet filled with meats, fish, and vegetables accounts for 97% of mineral intake, so there's no need to worry. Or is there? Is reverse osmosis water unusually leeching of minerals in some way?

I'm not that worried for myself because I add in keto salts for my water while fasting, so my water is already remineralized. But is it bad for a growing child? I'm not feeding my family the typical SAD diet, they get the best home cooked meals made with fresh groceries that we can afford.

Why are you doing reverse osmosis on your water? It sounds like an expensive way to treat it with no obvious benefit.

The intuition for why distilled water is bad, is that it will leech out minerals from your cells through osmosis. Obviously, there are no human trials to prove this, as is pointed out below (do note that the paper cited in that comment is not peer reviewed, and only "published " on researchgate, so take it with a grain of salt). It is entirely possible that this is a story made up by chemistry teachers to keep students from drinking it. This has historically not been studied, as distilled water is expensive and there is no obvious reason for drinking it instead of tap/bottled water.

I would say "ask your doctor", but frankly your dietary choices seem speculative enough that there won't be significant amount of research done on them, and so no real authoritative evidence in any direction.

I think you need to face that you are running a dietary experiment here. You are going to have to be the expert.

I've at least heard this claim uncited before. Isn't reverse osmosis filtering pretty ubiquitous on ships these days? I'm not aware of any literature suggesting major health impacts from this to sailors or long-term cruise passengers, for example. But maybe tossing in a multivitamin wouldn't be terrible.

ETA: I assume desalination plants like those in the news in the Middle East also use RO.

I got it from chemistry teachers and people working in labs. It might just be something they say to keep people from drinking it. Just like the story that the lab ethanol is treated with something that makes you puke, so that students won't steal it for their parties.

According to the research I remember it's more like "don't drink distilled water regularly" than "one glass and you suffer", and only the latter story would make sense as being made up so students don't drink lab-quantities of it.

As for technical ethanol, pretty sure they do treat it to taste foul at least.

We are talking about replacing your daily water intake entirely. I agree that the claim seems unlikely when you consider it seriously though. The more relevant question is why would you want to distill your drinking water in the first place?

My local groundwater was contaminated and has been the focus of a regional cleanup effort over decades, with the cleanup pumps are still actively filtering the water. About half of my neighbors have both water softening and a undersink RO system for their families. It wasn't that expensive compared to buying bottled or delivered water either, about $300 for the RO system and ~$150 in yearly replacement filters.

At least some people are using distillation or reverse osmosis for desalination. I'd do that too if my only water supply was the ocean.