pH
Cities measured
87
Detected in
87 / 87
Highest
8.1 — Stockholm
Overview
pH measures the acidity or alkalinity of water on a scale of 0–14, where 7 is neutral. Stockholm tap water typically reads 7.5–8.5 — slightly alkaline due to lime dosing during treatment. pH governs the solubility of metals, the efficiency of chlorine disinfection, and the taste of water.
Health Relevance
Water below pH 6.5 is corrosive and leaches lead and copper from pipes into drinking water. High pH (> 8.5) causes a bitter taste and can irritate skin. The body tightly regulates blood pH regardless of drinking water pH — the stomach immediately acidifies any ingested liquid to ~pH 2.
Regulatory Limits
Drinking Water Directive 2020/2184
6.5 – 9.5
EU Drinking Water Directive indicator parameter.
Controversy & Contested Science
The 'alkaline water' industry — a multi-billion-dollar sector — markets water at pH 8–10 as delivering anti-aging, anti-cancer, and enhanced hydration benefits. Independent systematic reviews find no credible evidence for these claims beyond normal hydration. The stomach neutralises any alkalinity within seconds of ingestion. In 2022, the European Food Safety Authority (EFSA) rejected all submitted health claims for 'alkaline water'. Critics argue the industry exploits scientific-sounding language to sell filtered tap water at 50–100× the cost.
Note
pH stands for 'potential of Hydrogen'. The scale was invented by Danish chemist Søren Peder Lauritz Sørensen in 1909 while working on protein stability at the Carlsberg Laboratory in Copenhagen.