What are the World Health Organization's guidelines for drinking distilled water?

1. WHO’s formal posture: “insufficient evidence” rather than prohibition

WHO’s most recent consolidated position is cautious: the Guidelines for Drinking‑water Quality state there is “insufficient scientific information on the benefits or hazards of long‑term consumption of very low mineral waters to allow any recommendations to be made,” which effectively means WHO neither recommends nor forbids drinking distilled water ^[1]. Historical WHO material from earlier decades treated demineralized water as acceptable for consumption under many circumstances, but the organization has since refrained from issuing a definitive health endorsement because the older studies were judged not to meet current scientific standards ^{[4] [3]}.

2. Why WHO flags minerals in drinking water as a public‑health consideration

WHO guidance underscores that water can contribute micro‑ and macro‑nutrients such as calcium, magnesium and sodium to diets, and that very low‑mineral waters like distilled water cannot supply these trace nutrients—an issue that matters at the population level in communities with marginal dietary intakes ^{[1] [2]}. The WHO literature and reviews cited in public reporting therefore frame the question not as distilled water being intrinsically dangerous, but as potentially less beneficial than mineral‑containing water for some population groups or dietary contexts ^{[1] [3]}.

3. Practical clinical and consumer perspectives: “safe, but context matters”

Medical and consumer health outlets consistently report that distilled water is safe to drink for most individuals if the person has a balanced diet, but they warn distilled water’s lack of minerals gives it a flat taste and means it won’t replace dietary sources of calcium or magnesium ^{[5] [6] [7]}. These sources recommend caution for specific groups—athletes with heavy electrolyte losses, malnourished people, or those with certain medical conditions—because distilled water will not replenish electrolytes lost through sweat, vomiting, or diarrhea ^{[2] [5] [7]}.

4. Reported risks and technical concerns WHO flagged in past reviews

WHO‑commissioned or referenced reports have historically noted possible issues with demineralized waters: poorer taste and thirst‑quenching, sparse and methodologically weak reports of gastrointestinal surface changes, and theoretical concerns that very low‑mineral water might be “aggressive” toward storage materials, potentially leaching container substances if stored improperly ^{[1] [4] [8]}. WHO’s stance reflects these mixed signals: the agency flags potential concerns but sees the evidence as inadequate to support broad health mandates ^{[1] [8]}.

5. What the guidelines do — and do not — tell policy makers and consumers

WHO’s Guidelines for Drinking‑water Quality set contaminant limits and emphasize preventing microbial and chemical contamination; they do not set a single global rule that distilled water is unsuitable for drinking but advise that mineral content and population nutritional status should inform local water‑supply decisions ^{[3] [1]}. In short, WHO treats distilled water as one type of potable water whose suitability depends on context—dietary mineral intake, storage practices, and the need to avoid waterborne illness—not a categorical public‑health hazard ^{[1] [3]}.

6. Reporting limitations and where evidence is thin

Available sources reiterate WHO’s “insufficient evidence” conclusion and cite older studies or WHO‑era documents; however, none of the provided materials offers a recent randomized trial or population study proving long‑term harms or benefits of drinking distilled water specifically, so public guidance remains dependent on expert judgment and local nutritional context rather than hard global rules ^{[1] [4] [3]}. Where the sources diverge—consumer sites urging routine use versus WHO cautioning about low mineral content—WHO’s official neutrality reflects a deliberate gap in conclusive science ^{[1] [5] [6]}.