Phuket: water and climate · 5 min · 17 September 2026
How much water to drink in Phuket heat
80% humidity changes the rules: how much to drink and what to add.
In short: the baseline is around 30 ml per kilogram of body weight, plus 0.5–1 l in the heat or under exertion. Part of that volume is easily covered by mineral water.
Why you drink more in the tropics
Humidity on Phuket sits at about 80%, so sweat barely evaporates: the body keeps sweating but cools less efficiently. You lose fluid even walking to the car. Indoors, air conditioning adds to it by drying the air, which draws water from your skin and your breath. The more you sweat, the more you lose not only water but salts too: sodium, potassium and magnesium.
- In humid air, sweat evaporates poorly
- Air conditioning dries out the air indoors
- The more you sweat, the more salts you lose
How much water should you drink a day on Phuket?
A simple guide is 30 ml per kilogram of body weight: at 70 kg that comes to a little over 2 l a day. For a temperate climate EFSA considers 2 l adequate for women and 2.5 l for men, counting water from food, and in the heat or under exertion you should add another 0.5–1 l. The easiest self-check is urine colour: pale yellow is fine, dark means it is time to drink. Our water calculator will give you a closer figure.
- Baseline 30 ml per kg of body weight, plus 0.5–1 l in heat or under exertion
- Signs you are short: dark urine, headache and no energy
- Our water calculator will give you a closer figure
How to replace minerals
Sweat takes more than water with it. Sodium, potassium and magnesium come back through food and mineral water: a litre of Narzan holds 200–600 mg of calcium and 50–180 mg of magnesium according to the label. A glass or two after a hot day is enough, with the rest of the volume made up with table water. Sugary soft drinks and alcohol are no help here: sugar returns no salts, and alcohol acts as a diuretic. This is general information, not medical advice.
- Mineral water with magnesium and calcium
- Food: fruit, soups, salt in your meals
- Sugary soft drinks and alcohol do not help