How much water to store for an emergency
For a power outage, a water cut or any emergency, water comes first in the kit.
Every figure has its official source at the end.
All of this, put into a plan for your home, is in the guide Ready in 7 Days.
How much per person
- 3 litres of water per person per day, just for drinking; more is needed for cooking and washing.
- Have enough for 3 days: 9 litres each, just to drink.
- Children, nursing mothers and people who are ill may need more.
What to buy
Bottled water
The simplest option, from the supermarket. Keep it sealed in its original container, somewhere cool and dark.
Water container with a tap
To store tap water and pour it without tipping the whole container. Food-grade, and washed with soap and water before you fill it.
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The rest of the kit, in levels and with what each one costs, in the kit.
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How to store it
- Keep bottled water sealed, in its original container, somewhere cool and dark.
- Tap water you store yourself goes in clean, food-grade containers, and gets replaced every 6 months.
- Never in containers that have held chemicals such as bleach or pesticides.
If the tap water is not safe
- A boil water notice means tap water might contain bacteria, viruses or parasites: bring it to a rolling boil and let it cool before drinking it or using it for food.
- A rolling boil is enough. Let it cool on its own, without adding ice, and keep it covered.
- If the supply is cut, your water company's website says where to get water nearby; if you are on its Priority Services Register, it arranges water for you.
Sources
Checked on 02/11/2026.
- Ready.gov (FEMA), "Water"
- UK government (Cabinet Office), Be Ready: "Be ready for emergencies"
- CDC, "How to Create an Emergency Water Supply"
- Drinking Water Inspectorate (DWI), "Receiving a Boil Water Notice"
- WHO, "Boil water", technical note WHO/FWC/WSH/15.02
- UK government (Cabinet Office), Be Ready: "Water supply interruptions or outages"
This does not replace instructions from the authorities or 999: if they say something different, do what they say.
Your home's water, in 20 minutes
In Ready in 7 Days, day 2 is water: you work out your home's numbers in its table, with what you already have, and store it with the date written on it so you know when to replace it.
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