How to Drink in Heat: Temperature, Coffee and Tap Water Explained

Overview

• Drink temperature affects net heat loss because very cold drinks cool the gut but can reduce sweating and skin evaporative cooling, so warm or body‑temperature fluids often work as well and slush or ice is best avoided during exercise in hot, dry conditions.
• Moderate, habitual coffee contributes to daily fluid balance much like water, but people who rarely drink caffeine can lose net fluid after large, acute coffee intake and should add water in that case.
• Simple universal targets are outdated; German nutrition guidance recommends roughly 1.5 liters a day as a baseline and advises sipping about 0.2‑liter glasses every one to two hours in heat, with needs rising for heavier activity or poor acclimatization.
• In Germany tap water is generally safe and more climate‑friendly than bottled water, yet household plumbing can reintroduce contaminants such as lead, nickel or residues from armatures so running cold water briefly before drinking is sensible.
• Regulatory monitoring of PFAS and other contaminants is ongoing across the EU, consumer tests to date found no critical PFAS in sampled mineral waters, and consumers should watch local water reports while regulators complete further testing.