El Nino Watch
Water is the first El Nino risk on Samui. WHO: 2.5-3 L per person per day just to survive (drinking and food), 7.5-15 L for basic needs. In the heat, drinking needs rise.
Preparedness
Why: Samui's reservoirs are small, the mainland pipeline covers under half of demand (see Samui's water supply), and a strong El Nino raises the odds of a long, hot dry season.
Reference amounts (WHO Technical Note 9): survival needs of 2.5-3 L per person per day (drinking and food); basic hygiene 2-6 L; basic cooking 3-6 L; total basic needs 7.5-15 L. FEMA advises at least 1 gallon (3.8 L) per person per day, and notes that needs can double in hot climates.
Keep a sealed drinking stock, keep the house tank full and clean, and know how to treat water (boiling for 1 minute, or unscented household bleach at the dose on Ready.gov).