How much water to store for an emergency (UK)
Water is the first thing to sort, because a water cut or a contaminated supply turns into a problem within hours. The UK government's figure is simple: 3 litres of drinking water per person per day, for three days.
The short answer
9 litres per person for three days (3 litres a day). A family of four needs 36 litres of drinking water, about eighteen 2-litre bottles. That is the minimum: water for cooking, washing, baby formula, medical devices and pets comes on top.
Water for your household
| Household | Per day | For 3 days | Roughly |
|---|---|---|---|
| 1 person | 3 litres | 9 litres | 4 × 2-litre bottles |
| 2 people | 6 litres | 18 litres | 9 × 2-litre bottles |
| 3 people | 9 litres | 27 litres | 14 × 2-litre bottles |
| 4 people | 12 litres | 36 litres | 18 × 2-litre bottles |
| 5 people | 15 litres | 45 litres | 22 × 2-litre bottles |
| 6 people | 18 litres | 54 litres | 27 × 2-litre bottles |
Count babies and children as full people: it keeps the sums simple and leaves a margin.
How to store it
- Shop-bought bottled water is the safest choice for drinking.
- Keep it in a cool, dark place, away from chemicals and sunlight.
- Write the month you bought it on each pack and replace it by its best-before date. Rotating it twice a year, when the clocks change, is easy to remember.
- Before a forecast storm, you can also fill clean containers with lids from the tap. Use that water first, for washing, flushing and cooking, and don't keep it for weeks.
- Purification tablets are a fallback if you have no space at all for bottled water. Follow the label: strengths differ, and most other water sources need filtering first.
When the tap stops
Use stored water for what matters most:
- Use stored water for the things that matter most: drinking, washing your hands and preparing food.
- Wash hands from a large clean bowl with soap, rather than under a running bottle.
- Use paper plates and cups for a day or two rather than washing up.
- Flush the toilet by pouring a bucket of non-drinking water briskly into the bowl.
Never drink water from a water butt. It is fine for flushing the toilet.
Boil-water notices
- Boil-water notice: bring the water to a rolling boil and let it cool. Store it covered in the fridge and throw it away if not used within 24 hours.
- Use boiled water for drinking, brushing teeth, making ice, preparing food, cleaning baby feeding equipment and giving water to pets. Keep boiling until the notice is lifted.
Questions people ask
How much water do I need per person for an emergency in the UK?
3 litres of drinking water per person per day. For the three days the government asks households to plan for, that is 9 litres per person.
How much water should a family of 4 store?
36 litres of drinking water for three days, roughly eighteen 2-litre bottles. Add extra for cooking, washing, formula and pets if you have room.
Can I store tap water for emergencies?
Filling clean, lidded containers from the tap before a forecast storm is useful, but use that water first and don't keep it for weeks. For your drinking supply, shop-bought bottled water is the safest choice.
Do I need extra water for a baby?
Yes, and for babies ready-to-feed formula is the safest option in an emergency, because you may not be able to boil water or sterilise bottles.
What should I do under a boil-water notice?
Bring the water to a rolling boil and let it cool. Store it covered in the fridge and throw it away if it is not used within 24 hours. Keep boiling until the notice is lifted.
Official sources
Checked against these official pages in October 2026. Advice and phone numbers can change, so the official page always has the final word.