The claim that distilled water is unsuitable for drinking is repeated widely and is partly true and partly not. It is not unsafe, and the alarming versions of the argument do not survive contact with the evidence. But there are real reasons it makes a poor everyday drinking water, and they are worth separating from the ones that do not hold.
The claim that does not hold
The strong version says distilled water leaches minerals out of the body because it is aggressive and seeks to dissolve whatever it contacts. Water is indeed a solvent, and distilled water does readily take up carbon dioxide from air and can be corrosive to some metals. It does not strip minerals from a person. Drinking water contributes a small share of dietary calcium and magnesium next to food, and stomach contents dominate the chemistry within moments of swallowing. This is the part of the claim to set aside.
The reasons that do hold
Three, and they are practical rather than dramatic. It contributes no dietary minerals at all, which matters at the margins for anyone whose diet is already poor or whose intake is very high through heat or heavy work. It tastes flat, because taste in water is largely its dissolved minerals, and drinks made with it are noticeably duller. And it is slow and energy hungry to produce at home, which makes it an odd choice for everyday volume when reverse osmosis achieves a similar result far more efficiently.
Where the mineral question genuinely matters
Not in people, but in some uses. Aquariums and hydroponics need mineral content and distilled water must be remineralized deliberately before use. Coffee brewing is measurably worse with zero mineral content, since extraction depends on it. Where distilled water is the household's sole drinking supply for long periods, adding a remineralizing stage is worth doing, and that is exactly what commercial systems do. The USGS classes water as soft at 0 to 60 mg/L as calcium carbonate, and distilled sits well below the bottom of that band.
When it is exactly the right choice
Where the source is unknown or badly contaminated and nothing else is available, since distillation removes essentially everything that does not evaporate with the water. Where nitrate or arsenic are present and a membrane is impractical. And for equipment: steam irons, humidifiers, CPAP machines and car batteries all benefit from water with no mineral content to deposit. So the honest answer is that distilled water is a specialist tool used well and an inefficient everyday drinking water. Our drinking water guide covers the alternatives.
Questions people ask about why distilled water is not suitable for drinking
Does distilled water leach minerals from your body?
No. Drinking water is a small contributor to dietary calcium and magnesium, and stomach contents dominate the chemistry immediately.
So why avoid it as an everyday drink?
It tastes flat, contributes no minerals, and is slow and energy hungry to make at home when reverse osmosis achieves a similar result.
Can it be made suitable?
Yes. A remineralizing stage restores minerals and taste, which is what commercial systems do as a matter of course.
When is distilled water the right choice?
For badly contaminated or unknown sources, and for steam irons, humidifiers, CPAP machines and batteries where minerals would deposit.