Water calculator for sailing passages
How much water your crew needs, whether your tanks are enough, and how much sealed emergency water to carry.
- Water needed
- 702 L
- Short by
- 102 L
- Full tanks last
- 20 days
- Sealed emergency water
- 60 L
4 crew × 7.5 L × 23.4 days. Emergency water at the survival level (3 L per person per day) for 5 days, kept apart from the tanks.
Where the figures come from
The levels follow the World Health Organization's Technical Note No. 9, “How much water is needed in emergencies” (prepared by WEDC for WHO): survival needs of 2.5–3 litres per person per day for drinking and food, basic cooking 3–6 litres and basic hygiene 2–6 litres — 7.5–15 litres in all. Tank sizes for listed boats are manufacturer figures from broker and charter listings; your boat may differ.
Questions
How much water per person per day on a boat?
The World Health Organization puts survival needs (drinking and food) at 2.5–3 litres per person per day, and basic needs including cooking and basic hygiene at 7.5–15 litres. Heat and hard work raise the drinking figure.
How much emergency water should I carry?
Keep sealed water apart from the tanks, so a contaminated tank or a failed pump doesn't leave you without. The calculator sizes it at the survival level of 3 litres per person per day for the number of days you choose.