Skeptics Stack Exchange is a question and answer site for scientific skepticism. It only takes a minute to sign up.
Sign up to join this community
Claim: Drinking distilled water can actually remove needed minerals from the body, due the lack of minerals in the water, and therefore do damage to the body.
I have a hard time accepting this due to amount of minerals that can be found in the body. However, I know that you can drown the body by drinking to much water and that body does use water to remove waste from it cells.
This is true.
I did some digging: the Wikipedia article on water purification linked to a study by the WHO that discusses the risks of drinking demineralised water.
It states
It has been adequately demonstrated that consuming water of low mineral content has a negative effect on homeostasis mechanisms, compromising the mineral and water metabolism in the body
This means that it interferes with the body's attempts to keep the pH and mineral composition of internal organs constant, which is a more exact way of saying that it removes minerals from your body.
It reports some of the effects:
Results of experiments in human volunteers evaluated by researchers for the WHO report are in agreement with those in animal experiments and suggest the basic mechanism of the effects of water low in TDS (e.g. < 100 mg/L) on water and mineral homeostasis. Low-mineral water markedly: 1.) increased diuresis (almost by 20%, on average), body water volume, and serum sodium concentrations, 2.) decreased serum potassium concentration, and 3.) increased the elimination of sodium, potassium, chloride, calcium and magnesium ions from the body.
The report warns of other indirect downsides of demineralised water, including corrosion of pipes, and reduction of minerals from food cooked with it.
Ref: Health Risks From Drinking Demineralised Water, Frantisek Kozisek, Water safety plan manual: Step-by-step risk management for drinking-water suppliers, 2009, Chapter 12.
This is not true, not in any meaningful sense.
First of all, non-distilled water has extremely widely varying levels of various minerals; for example among U.S. cities magnesium concentration varies by 300-fold (and other minerals also vary widely). Since leeching is proportional to concentration difference, the difference between zero and a tiny trace is much less chemically significant than the difference between a tiny trace and a 300-fold larger trace.
Second of all, the minerals in drinking water are, for a balanced diet, overwhelmed by the minerals present in food. For example, in the U.S. cities list, if you drink 2L of water of the highest mineral concentration, you would get 120, 180, 220, and 30 mg of magnesium, calcium, sodium, and potassium, respectively. The daily recommended intake (linked from here) for 19-30 year old males is 400, 1000, 1500, and 4700 mg. These differences are vast, and are similarly large for the other minerals I've checked. Certainly, since water has no memory, drinking distilled water wouldn't take away more than 120 mg of magnesium beyond what drinking the highest magnesium concentration tap water in the U.S., and this is a negligible amount compared to the daily intake.
However, if one has poor nutrition to begin with, water may provide (no guarantees, given the large variations!) enough of some mineral to alleviate negative impacts on health. Still, that distilled water is "removing minerals" is not a useful way to think about it. Yes, of course when we excrete waste products, some minerals go along; if you're short of some mineral, you'll then be even shorter. If you're lucky enough to have the deficiency covered by the water you drink, then you'll of course do better if you don't change water supplies. But the mineralization of water is widely variable, and it is not the distinction between distilled and undistilled but the particular concentration of particular minerals in particular water that is important. For example, if you're desperately short of calcium, 180 mg/day from water is going to be a lot better for you than 0 mg/day!
Short version: mineral content in water has a minimal to negligible impact in the context of good nutrition; it is possible for there to be enough of a mineral in a water supply to make a difference in the context of poor nutrition.
The available evidence suggests:
This topic is covered by two reviews of literature with the opposing results: one by World Health Organization and one by Water Quality Association.
A 2005 report by World Health Organization (WHO), Chapter 12: Health risks from drinking demineralized water
This review includes an earlier statement by WHO from 1980:
Salts are leached from the body under the influence of drinking water with a low TDS. (TDS = total dissolved solids, which is basically mineral content.)
The author also says:
Results of experiments in human volunteers evaluated by researchers for the WHO report are in agreement with those in animal experiments and suggest the basic mechanism of the effects of water low in TDS (e.g. < 100 mg/L) on water and mineral homeostasis. Low-mineral water markedly: 1.) increased diuresis (almost by 20%, on average), body water volume, and serum sodium concentrations, 2.) decreased serum potassium concentration, and 3.) increased the elimination of sodium, potassium, chloride, calcium and magnesium ions from the body.
In the above paragraph, there is a mixture of things that don't go together: the increase of both "body water volume" and "diuresis," and increase of both "serum sodium concentration" and "elimination of sodium."
My only explanation is that they mixed the results of various types of studies. For example, drinking usual amounts of distilled water (compared to isotonic beverages) increases diuresis, but not the "body water volume" (Nutrients, 2017; Table 3 and 4). On the other hand, drinking excessive amounts (several liters) of any water, not just distilled, in a short time (few hours) increases the "body water volume" (Stat Pearls, 2019). These are two totally different scenarios, so the results in the above review seem to be really mixed up.
Next, in the report, every water with less than 100 mg minerals per liter seems to be considered demineralized, while by definition, demineralized water contains less than 10 mg minerals per liter (EPA.gov). About 80 cities from a list of 100 big US cities have less than 100 mg/L of minerals in tap water, so does this mean that their tap water is harmful for health?
A 1993 review by Water Quality Association: Consumption of low TDS water is basically a critic of the already mentioned statement by WHO from 198O (refered below as the "Soviet report") that salts are leached from the body under the influence of drinking water with a low TDS.
It has been concluded that the consumption of low TDS water, naturally occurring or received from a treatment process, does not result in harmful effects to the human body.
Several types of scientific literature searches have found no harmful effects to the human body attributable to the consumption of low TDS water.
Review of the Soviet report has shown that the scientific methods used are questionable and the conclusions are either vague or unsupported by the data.
Many examples of real-world situations in which large populations have been and continue to be provided exclusively with low TDS water without any reported unusual or ill health effects, establishes the safety of consuming such waters by human beings.
Can drinking distilled water result in water intoxication (dilutional hyponatremia)?
Only if you drink it in large amounts in a short time; it can occur with any water, not just distilled water. Distilled water has no sodium and has low osmolality (0 mmol/kg), but this is very similar to tap water which usually has <10 mg sodium/liter (Mgwater) and osmolality as low as 3 mmol/kg (SGSM.ch, Table 2). A woman has died after drinking ~6 liters of regular water in 3 hours (Scientific American). A bit more in detail on Medical SE.
Does drinking distilled water dehydrate you?
No, distilled water can hydrate you about as well as average tap water, because, as said, distilled and tap water may not be that different in mineral content and osmolality. In general, the hydration potential of a beverage increases with its sodium content (as explained in another answer).
