UK: drinking-water planning
The UK Be Ready figure is 3 litres per person per day for drinking. The 3 litres per person per day is drinking water. Cooking, washing and other uses need additional water. The manuscript also gives around 10 litres per person per day as a broader comfort planning figure including basic cooking and hygiene.
US: CDC water baseline
The CDC baseline is at least 1 US gallons per person per day. The CDC baseline is at least 1 US gallon per person per day for drinking, cooking, brushing teeth and other uses; circumstances can require more. This is a US liquid gallon, not a UK imperial gallon. The CDC advises trying to store a two-week supply if possible. A US gallon is not a UK imperial gallon.
Worked calculation for four people over three days
| Planning basis | Calculation | Total |
|---|---|---|
| UK drinking water | 3 × 4 × 3 | 36 litres for drinking, plus recipe water and other household needs. |
| UK broader comfort planning | 10 × 4 × 3 | 120 litres overall |
| US CDC baseline | 1 × 4 × 3 | 12 US gallons for four people over three days. The CDC advises trying to store a two-week supply if possible. |
Recipe water is separate. About 2.15–2.55 litres for the source menu's recipes. Reserve at least 3 litres for recipe water, with more contingency. Keep the UK's drinking-water allocation separate. For the US CDC baseline, do not count the same recipe water twice.
Water notices and safe use
Follow your water supplier or local public health instructions. A boil-water notice and a do-not-drink or do-not-use notice are different. Boiling does not remove chemical contaminants. Use water from a safe source when directed; a filter jug is not a general emergency purifier.
Official sources
UK Be Ready household checklist ↗UK campaign announcement ↗US emergency supplies — Ready.gov ↗US emergency food — USDA FSIS ↗US emergency water — CDC ↗EU preparedness strategy ↗UK FSA (GOV.UK): food safety in a power cut ↗FDA: food and water safety during power outages ↗CDC: drinking-water advisories explained ↗Source links and principal guidance claims checked 2 November 2026. Consult current local advice. The Blackout Kitchen is independent and is not endorsed by these organisations.