What this site does not cover, and why

The rule we are following

Every ActSmall topic operates on a single editorial rule: where the named public-health authorities converge, we display it; where they diverge or are silent, we do not invent a position. The named bodies for drinking-water safety are the World Health Organization (WHO), the WHO/UNICEF Joint Monitoring Programme (JMP), the US Centers for Disease Control and Prevention (CDC), the US EPA, and the equivalent national agencies in each country. Where they have converged, we cite them. Where they have not, we say nothing.

Community-water fluoridation

Community-water fluoridation (the recommended level of added fluoride is ~0.7 mg/L in the US, set by CDC/HHS since 2015; the separate WHO guideline value of 1.5 mg/L is a ceiling for naturally occurring fluoride, not a fluoridation target) is the most-litigated single intervention in modern drinking-water public-health policy. The WHO, the US CDC, the American Dental Association, and the equivalent UK and Australian dental and public-health bodies all publish the position that community fluoridation at recommended concentrations is a safe and effective dental-caries prevention measure^[1]. The legal and political picture is more complex — several European countries do not fluoridate community water (using salt fluoridation or topical fluoride programmes instead), and US municipalities continue to vote on adding or removing fluoridation. We cite the named bodies' positions on dental health. We do not include a "fluoridation status" map layer because the underlying decision is a municipal-policy question, not a household action, and rating municipalities globally on a single political choice does not produce a useful map.

"Alkaline", "structured", "hexagonal", and "hydrogen-rich" water

The consumer water-product market includes alkaline ionizers, "structured water" devices, "hexagonal water" claims, and bottled "hydrogen-rich" water. There is no peer-reviewed clinical evidence that the WHO, CDC, or any major drinking-water-quality authority has endorsed for the health claims attached to these products at consumer exposures. The WHO's drinking-water guidelines specify the parameters that matter (microbiological, chemical, radiological, acceptability) and do not include water "structure", pH at the consumer tap, or molecular hydrogen content as health-relevant indicators^[2]. We do not repeat these claims and we do not rate brands that make them.

Brand-by-brand household filter rankings

"What is the best home water filter" is the single most-asked consumer question in this topic. We do not answer it with brand names. The reason is that NSF International (and its equivalents WQA, IAPMO R&T) publish open contaminant-reduction certifications — NSF/ANSI 42 (aesthetic), 53 (health-effects), 401 (emerging contaminants), 58 (reverse osmosis), and 244 (filtration of microbial cysts)^[3]. Any product certified to the applicable standard for the contaminant of concern in your tap water is sufficient; "the best brand" is a question the standard already answers. We name the standards to look for and link to the named certifiers' product-finder tools rather than maintaining a brand list that would go out of date.

Bottled water versus tap

In most high-income countries with regulated municipal water systems (the EU, the US, Canada, the UK, Australia, New Zealand, Japan, and large parts of East Asia and Latin America), properly regulated tap water is held to the same WHO drinking-water quality criteria as packaged water, so bottled water has no inherent public-health advantage and may carry worse environmental and microplastic-exposure profiles^[4]. In low-income countries and emergency contexts, the calculus is very different and the WHO, UNICEF, and IFRC have separate guidance for those contexts. We cover the headline statistic (the JMP "safely managed" indicator) and the structural water-access situation; we do not produce a bottled-versus-tap recommendation that would be wrong for a third of the readership.

National water-rights politics

Transboundary water disputes (the Nile, the Mekong, the Indus, the Colorado, the Jordan), upstream-versus-downstream allocation under climate stress, and the legal-personality status of rivers and lakes (the Whanganui in New Zealand, the Atrato in Colombia) are real and important policy topics. We do not take a side. The reason is the same as for nuclear policy in the ground topic: these are political-allocation questions with multiple legitimate parties, not single-best-action household-water questions. Where the UN Water, UNECE, or the named treaty-monitoring bodies have published positions, we link to them as references; we do not assert a "correct" allocation.

PFAS, lead, and emerging contaminants

This is the one area where the named authorities have moved fast in the last five years. We do cover lead service-line replacement (the EPA Lead and Copper Rule, and the UK’s lead-pipe replacement duty under the Water Supply (Water Quality) Regulations, overseen by the Drinking Water Inspectorate), and we cover the WHO and EPA published positions on PFAS where they exist (the 2024 EPA national PFAS drinking-water standard sets individual limits for five PFAS plus a hazard index for certain mixtures). We do not cover speculative claims about microplastics in drinking water, for which the WHO has explicitly said the evidence does not yet support a health-based guideline value^[5].

Where this leaves us

The water topic covers what the WHO, JMP, CDC, and EPA have converged on: safely-managed drinking water access (JMP indicator), basic sanitation, the WHO drinking-water guidelines core chemical and microbiological parameters, lead-pipe replacement, and PFAS where MCLs exist. Where the named authorities are silent or where the question is policy rather than household action, we say so.