Water
How much water should you store?
How much drinking and household water to keep for an emergency, how to store it safely, and when to replace it. With litres, UK gallons and US gallons.
Reviewed
Food & water · Free tool
Emergency Water Storage Calculator
Find out how much water to store for your household and pets, in litres and UK and US gallons, with container counts and rotation reminders.
Last reviewed
How to use it
- Enter the number of adults and children, and how many of them are pregnant or breastfeeding.
- Choose how many days to plan for, the climate and whether you want extra water for hygiene.
- Add any dogs (by size) and cats.
- Read your total and container counts, then print or download the plan.
Your water plan
Store about 24 L for 3 days. That is 8 L a day.
- Total in litres
- 24.0 L
- UK (imperial) gallons
- 5.3
- US gallons
- 6.3
Where the water goes
| Use | Per day | Total |
|---|---|---|
| Drinking | 6 L | 18 L |
| Cooking and hygiene | 2 L | 6 L |
| Total | 8 L | 24 L |
Containers you would need
Choose one size or mix them. Counts are rounded up.
- 5 × 5 litre containers
- 3 × 10 litre containers
- 1 × 25 litre container
Keeping it fresh
- Shop-bought bottled water: replace by the date printed on the bottle.
- Water you have filled yourself from the tap: replace every 6 months.
- Store containers somewhere cool and dark, away from chemicals and fuel.
- If you are unsure whether water is safe, treat it first. See emergency water purification.
How this is calculated
The calculator adds up a daily allowance for each person and pet, then multiplies it by the number of days.
The planning basis
We plan 4 litres per person per day in total, for children and adults alike:
- 3 litres for drinking. This matches the drinking-water figure in the UK government’s Be Ready checklist (3 litres per person per day).
- 1 litre for cooking and basic hygiene.
For comparison, US guidance from Ready.gov uses 1 US gallon per person per day (about 3.8 litres) for drinking and sanitation together. Our 4 litres is close to that, rounded to a figure that is easy to plan with.
Adjustments
| Situation | Extra per day |
|---|---|
| Hot climate or heatwave | +1 litre per person (drinking) |
| Pregnant or breastfeeding | +1 litre per person (drinking) |
| Extra hygiene | +2 litres per person (cooking and hygiene) |
| Small dog | 0.5 litres |
| Medium dog | 1 litre |
| Large dog | 1.5 litres |
| Cat | 0.25 litres |
Converting units
- Total litres ÷ 4.546 = UK (imperial) gallons.
- Total litres ÷ 3.785 = US gallons.
- Containers are the total divided by 5, 10 or 25 litres, rounded up so you never fall short.
Assumptions and limits
- These are planning figures. Real needs rise with heat, exercise and illness, so store more if you can.
- Hygiene water here means basic washing. It does not include flushing toilets with mains-style volumes; plan separately if your water supply is likely to be off for long.
- Children are planned at the adult rate. This leaves a little margin for spills and waste.
- Pet figures are rough averages. They are not veterinary advice.
Frequently asked questions
How much water should I store per person?
This calculator plans 4 litres per person per day in total. About 3 litres of that is for drinking, and the rest for cooking and basic hygiene. Add more for hot weather, pregnancy or breastfeeding, and extra washing.
What is the difference between UK and US gallons?
A UK (imperial) gallon is about 4.55 litres. A US gallon is about 3.79 litres. We show both so that figures from UK and US guidance are not confused.
How often should I replace stored water?
Replace shop-bought bottled water by the date printed on it. Replace water you have filled yourself from the tap every 6 months.
Can I store tap water?
Yes, in clean, food-grade containers with tight lids, kept somewhere cool and dark. Label each container with the date you filled it.
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