Temperature
Cities measured
87
Detected in
87 / 87
Highest
32.8 °C — Riyadh
Overview
Water temperature affects taste, dissolved gas content, and microbial growth. Cooler water carries more dissolved oxygen and tastes better. Distribution pipe networks can warm water significantly between treatment plant and building tap.
Health Relevance
Water above 25°C encourages Legionella growth in pipes and water heaters. Cold water (< 12°C) inhibits most bacterial growth. Temperature has no direct health effect at normal tap water ranges.
Regulatory Limits
Drinking Water Directive 2020/2184
No EU regulatory limit. WHO recommends < 25°C.
Controversy & Contested Science
Legionella pneumophila thrives at 25–45°C in building pipe networks — particularly in apartment blocks, hotels, and hospitals with slow-flow or dead-end sections. The EU estimates ~10,000 reported Legionellosis cases per year, considered a severe undercount given that most mild cases go undiagnosed. Building design failures contribute more to Legionella risk than treated water quality, yet EU building plumbing regulations on thermal management are inconsistent across member states.