Emergency Water Storage Calculator
Work out how much drinking water your household should store, in litres or gallons, with the UK, German and US planning figures side by side and the arithmetic shown.
Water is the part of an emergency supply people most often underestimate, because the arithmetic is easy and the storage is not. Three days for one person fits in a cupboard. Two weeks for a family of four weighs about as much as three adults, and deciding where it goes is the real work.
Official figures also differ from country to country, so the calculator below shows the main ones together rather than pretending there is a single right answer.
Work out your household's figure
Your household
Store 46 litres
These are general planning figures, not medical ones. Ready.gov notes that children, nursing mothers and sick people may need more, and that in very hot weather needs can double. Anyone pregnant, unwell, on medication that affects hydration, or managing a condition such as kidney disease should take advice from their own doctor.
The pet figure is a rough allowance only. No agency we checked publishes a per-animal quantity, and a small cat and a large dog are very different. Ask your vet what your animal drinks, and see the pet emergency kit guide.
Never ration drinking water unless authorities tell you to. Ready.gov is explicit about this: drink what you need and look for more.
What the official figures say
| Authority | Per person per day | Covers |
|---|---|---|
| UK Government (citing the WHO) | 2.5 to 3 L (0.7 to 0.8 US gal) | Drinking, minimum for survival |
| Germany (BBK) | 2 L (0.5 US gal) | 1.5 L drinking, 0.5 L cooking |
| US (Ready.gov) | 3.8 L (1 US gal) | Drinking and sanitation |
| UK Government | 10 L (2.6 US gal) | "Will make you more comfortable" |
Two practical readings. First, the low figures are for drinking only. Washing, cooking and flushing all need more, which is why the UK's comfortable figure is three times its minimum. Second, every figure is a floor. Heat, illness, pregnancy, breastfeeding and physical work all raise it.
Common household totals
| Household | 3 days | 7 days | 14 days |
|---|---|---|---|
| 1 person | 11 L / 3 gal | 26 L / 7 gal | 53 L / 14 gal |
| 2 people | 23 L / 6 gal | 53 L / 14 gal | 106 L / 28 gal |
| 3 people | 34 L / 9 gal | 79 L / 21 gal | 159 L / 42 gal |
| 4 people | 45 L / 12 gal | 106 L / 28 gal | 212 L / 56 gal |
| 5 people | 57 L / 15 gal | 132 L / 35 gal | 265 L / 70 gal |
| 6 people | 68 L / 18 gal | 159 L / 42 gal | 318 L / 84 gal |
What it weighs, and where it goes
A litre of water weighs a kilogram (a US gallon about 8.3 lb). A family of four's two-week supply is around 212 kg (467 lb), and it needs somewhere cool, dark and structurally sound.
| Container | Holds | Weight, full | Practical notes |
|---|---|---|---|
| 6 × 1.5 L bottles | 9 L / 2.4 gal | 9 kg / 20 lb | Easiest to rotate and carry. Uses the most space per litre. |
| 5 L bottle | 5 L / 1.3 gal | 5 kg / 11 lb | Thin plastic, not designed for stacking or years of storage. |
| 10 L jerrycan | 10 L / 2.6 gal | 10 kg / 22 lb | A good balance of capacity and portability. |
| 20 L jerrycan | 20 L / 5.3 gal | 20 kg / 44 lb | About the heaviest most adults move comfortably. |
| 200 L drum | 200 L / 53 gal | 200 kg / 441 lb | Immovable once full and needs a pump. Check the floor can take it. |
Split storage across at least two places if you can, so a single flooded basement does not take all of it. If leaving home is a realistic scenario where you live, keep some of it in containers one person can lift.
Keeping it drinkable
Ready.gov advises buying commercially bottled water and keeping it sealed in its original container in a cool, dark place, using it by the printed date. For water you have bottled yourself, it advises replacing it every six months.
That six-month swap is where most water supplies quietly fail. Write the fill date on each container, and tie the check to something that already happens twice a year, such as the clocks changing. StayReady Kits stores the date against each container and reminds you before it is due, which removes the need to remember at all.
If you run out of stored water and need to make other water safe to drink, follow your public health authority's current instructions, such as the CDC's Making Water Safe in an Emergency, and any boil-water notice from your water company. Disinfection quantities depend on the strength of the specific product you have, so we do not reprint them on a page that could go out of date.
Boiling and household disinfection do not remove fuel, chemicals or radioactive material. If contamination of that kind is suspected, follow official instructions.
Common questions
How much water should I store per person per day?
At least 2.5 to 3 litres of drinking water according to the UK Government, or about 3.8 litres (one US gallon) for drinking and basic hygiene according to US Ready.gov. Ten litres is more comfortable.
How much does a family of four need for two weeks?
About 212 litres (56 US gallons) at 3.8 litres per person per day. It weighs around 212 kg (467 lb).
How long can I keep stored water?
Bottled water by its printed date, kept sealed, cool and dark. Water you bottled yourself, replace every six months.
Should I ration water?
No, unless authorities tell you to.
Sources
- UK Government, Prepare: get prepared for emergencies. Source of the 2.5 to 3 litre and 10 litre figures.
- Federal Office of Civil Protection and Disaster Assistance (BBK), Essen und Trinken bevorraten (in German). Source of the 2 litre figure.
- U.S. Department of Homeland Security, Water, Ready.gov. Source of the one US gallon figure, the six-month replacement interval, the storage advice, the note on heat and vulnerable groups, and the advice not to ration.
- Centers for Disease Control and Prevention, Making Water Safe in an Emergency. Referenced rather than reproduced.
Keep the figure right as your household changes
A total is only right on the day you work it out. A new baby, a dog or a growing child all change it. StayReady Kits recalculates your household's water target automatically, in litres or gallons, tracks what you have against it, and reminds you before stored water is due to be replaced. Free on the App Store, no account required.
Download on the App Store