Water
How Much Drinking Water Should You Store?
The official UK figure is 3 litres per person per day for drinking, for three days. Here is what that adds up to, and what official pages do not specify.
If you remember one number from official UK preparedness advice, make it this one: 3 litres of bottled water per person per day, for drinking, kept for three days.
That figure appears on the Be Ready checklist and again on the Prepare power-cut page (“at least 3 days’ worth of bottled water (3 litres per person per day)”). It is a drinking-water figure. The same Be Ready page says more water would be needed for cooking and washing, without stating how much extra.
What the official drinking figure adds up to
Using only the published drinking-water rate:
| Household size | 24 hours | 48 hours | 72 hours |
|---|---|---|---|
| 1 person | 3 litres | 6 litres | 9 litres |
| 2 people | 6 litres | 12 litres | 18 litres |
| 3 people | 9 litres | 18 litres | 27 litres |
| 4 people | 12 litres | 24 litres | 36 litres |
| 5 people | 15 litres | 30 litres | 45 litres |
Those 72-hour totals are simple multiplication: people × 3 litres × 3 days. They are not a medical prescription, and they are not a claim about how much water any one person will drink in hot weather or while ill.
The kit builder uses the same official calculation and updates the total when you change household size.
What official pages do not quantify
It would be easy to invent extra litre figures for washing up, flushing a toilet, pets or medical devices. This site will not do that.
- Cooking and washing. Official guidance says more water would be needed. No official extra volume is given.
- Pets. Be Ready lists bottled water for pets, without a litre amount.
- Baby formula. Ready-to-feed formula is preferred if you cannot boil water safely. Extra water for washing bottles is not given as an official volume.
- Medical devices. Some equipment uses water. Follow the plan from your clinician or supplier rather than a website guess.
A reasonable planning suggestion — labelled as such, not as official advice — is to fill clean containers from the tap if an outage is forecast, and to use that stored tap water for washing and flushing so bottled water can stay for drinking, handwashing and food preparation. Do not treat any made-up extra total as a government figure.
How to keep what you store
Official pages describe bottled water as the straightforward way to keep a standing drinking supply. Practical steps that follow from that, without adding unpublished science, are:
- Keep bottles sealed until you need them.
- Store them somewhere cool, dark and easy to reach — not behind a locked shed you cannot get to in the dark.
- Check dates when you review the rest of your kit (Be Ready suggests a reminder every six months).
- Rotate older bottles into ordinary use and replace them.
If your water company issues a boil-water notice, follow that notice rather than any general article.
Treatment tablets and filters can have a place in some situations, but they are not a substitute for official notices, and this site will not invent purification performance claims. See the draft companion article Best ways to store emergency drinking water for the planned structure of that longer how-to.
Why three days?
Be Ready frames three days as a period when households may need to manage while support reaches those most in need. The British Red Cross has described the wider 72-hour message as preparation for short disruption, not for a major disaster. Water is simply the part of that message with a clear published volume.
If money is tight, you do not need to buy a year’s supply. Adding a supermarket multipack during a normal shop, then another later, matches the campaign’s “build it gradually” advice.
Sources
- Be Ready for emergencies — “3 litres per person per day for drinking”
- Prepare: power cuts
- British Red Cross on 72-hour preparedness
Open the 72-hour kit builder · Free checklists and official links