Drinking water and food hygiene on Koh Samui

Water and food rules on Koh Samui are simple and widely agreed. Water: tap water is not safe to drink anywhere on the island; drink bottled water (available at every shop for a few baht) or filtered water, and use bottled water for brushing teeth if you have a sensitive stomach. Ice is reassuringly different: the cylindrical tube ice with a hole through the middle, standard in restaurants and stalls, comes from regulated factories and is generally considered safe; crushed ice of unclear origin is riskier in rural spots. Food: the honest summary is that most eating on Samui is safe, and street food is a highlight, not a hazard, when you choose well. Pick busy stalls with high turnover where food is cooked fresh and hot in front of you; high turnover means ingredients do not sit around. Be more cautious with pre-cut fruit, salads, uncooked seafood, and buffet dishes that have stood warm for hours, especially in your first days while your stomach adjusts. Wash or sanitise hands before eating; hand hygiene prevents more traveller's diarrhoea than food rules do. If you do get a stomach upset, the main treatment is fluids: oral rehydration salts from any pharmacy (a few baht) mixed with safe water, sipped regularly; eat lightly, avoid alcohol, and rest. See a doctor if there is blood in the stool, high fever, signs of dehydration (very little urine, dizziness on standing), or symptoms lasting more than two or three days, and take special care with children, who dehydrate fast.

Summary

Do not drink tap water on Koh Samui; bottled water is cheap and everywhere. Factory-made tube ice in restaurants is generally safe. Street food from busy stalls cooked fresh in front of you is usually fine; be more careful with pre-cut fruit, salads and buffets standing in the heat.

Key facts

• Tap water is not safe to drink on Koh Samui; use bottled or filtered water
• Factory tube ice (cylindrical with a hole) is generally safe
• Busy stalls with fresh, hot, cooked-to-order food are the safest street food
• Be cautious with pre-cut fruit, salads and long-standing buffets
• Oral rehydration salts are the main treatment for stomach upsets
• See a doctor for blood in stool, high fever, dehydration or symptoms beyond 2-3 days

Local tips

• Carry hand sanitiser and use it before every meal
• Choose the stall with the longest local queue
• Start gently with street food in your first two days
• Keep oral rehydration salts in your day bag during hot months