For most UK households, a practical target is 30 litres of emergency water per person. That provides 10 litres per person per day for three days, covering drinking plus limited cooking and basic hygiene. If space or cost makes that difficult, start with 9 litres per person, based on 3 litres of drinking water per day for three days, then build towards the fuller amount.
These are planning figures, not a promise that every incident will last three days or that everyone will use the same amount. A burst main may be repaired within hours, while flooding, a power failure, severe weather or trouble with a private supply can last longer. The useful question is not simply how much water fits in a cupboard, but how much safe water your particular household needs before outside help becomes available.
How much emergency water should you store per person?
The UK Government’s water outage guidance says there is no standard figure because emergencies and household needs vary. It gives two useful daily quantities:
- 2.5 to 3 litres per person per day as the minimum drinking-water quantity.
- 10 litres per person per day for greater comfort, including drinking, basic cooking and hygiene.
Three days is a sensible first target. Current local-authority emergency guidance, including Renfrewshire Council’s household preparedness advice, recommends keeping supplies for at least three days. Combining that period with the UK Government’s daily figures produces a simple two-level plan.
| People in household | Three-day drinking minimum | Practical three-day target |
|---|---|---|
| 1 | 9 litres | 30 litres |
| 2 | 18 litres | 60 litres |
| 3 | 27 litres | 90 litres |
| 4 | 36 litres | 120 litres |
| 5 | 45 litres | 150 litres |
The lower figure is a constrained drinking reserve, not a comfortable household allowance. It leaves little or nothing for preparing food, taking medicines, brushing teeth or washing hands. For that reason, 30 litres per person is the better target where storage space and budget allow.
Use a simple emergency water calculation
Calculate your baseline as follows:
Number of people × number of days × daily allowance in litres
For example, four people using the practical allowance need 4 × 3 × 10 litres, which is 120 litres. The same household’s drinking-only minimum is 4 × 3 × 3 litres, or 36 litres.
Do not stop at the basic calculation if any of the following applies:
- Babies and infant formula: allow for feeding and cleaning equipment. Ready-to-feed liquid formula is a useful emergency option if safe boiling and sterilising are not possible. Bottled water is not sterile, and the NHS formula preparation guidance should still be followed if it has to be used.
- Medical needs: add the quantity required for medicines, wound care, dialysis or any water-dependent device, following the care team’s instructions. Do not estimate a medical allowance from a generic household formula.
- Illness and hot weather: people may need more fluid when they have vomiting, diarrhoea or fever, or when they are sweating in hot conditions. Babies, young children and older adults can be more vulnerable to dehydration.
- Pets: store water in addition to the human allowance. Base it on the animal’s normal consumption, food type, size, health and veterinary advice, with extra for spillage and hot weather.
- Food: dried rice, pasta, dehydrated meals and powdered drinks consume part of the water reserve. Ready-to-eat food reduces both water use and the need for cooking fuel.
- Private or unreliable supplies: rural homes using a well, spring, borehole or electric pump may justify a longer reserve because a local fault can affect only one property and may take longer to resolve.
Should you store more than three days of water?
Three days is a useful baseline rather than an upper limit. Once that is covered, households with enough safe storage can extend the reserve to seven days. At the practical rate, this means 70 litres per person. A seven-day reserve is more reasonable for a remote home, a private water supply, an area with a history of prolonged interruptions, or a household with medical needs.
There is no need to buy a large reserve in one trip. Add one pack during an ordinary shop, keep a record of the total and stop when the planned quantity is reached. A smaller supply that is stored correctly and routinely checked is more useful than a large collection of forgotten or damaged bottles.
Choose water and containers that are practical to use
For most homes, sealed shop-bought bottled water is the simplest option. UK Government guidance recommends it over filling containers at home because it is sealed in a food-grade bottle for longer-lasting safety and quality.
- Use a mixture of sizes. Large containers use storage space efficiently, but smaller bottles are easier for children, older people and anyone with reduced grip or mobility to lift and pour.
- Remember the weight. One litre of water weighs approximately one kilogram, so a four-person practical reserve contains about 120 kilograms of water before packaging. Divide it between stable, low storage positions rather than putting everything on one shelf.
- Keep bottles sealed. Store them in a cool, dark place, away from direct sunlight, fuels, pesticides, cleaning chemicals and anything with a strong odour.
- Avoid temperature extremes. An uninsulated loft, greenhouse, shed or vehicle is generally a poor location because heat and freezing can damage packaging and make rotation harder.
- Follow the label. Check the manufacturer’s storage instructions and date marking. Use older bottles normally and replace them as part of the household shop rather than discarding good water unnecessarily.
In a small flat or rented home, spread manageable bottles across low kitchen cupboards, a ventilated under-stairs area or other accessible storage. Keep them away from boilers and heaters, do not block an escape route and make sure a leak would not damage electrical equipment or valuable documents.
Can you store tap water in refillable containers?
Yes, but it takes more care and is not the first choice in current UK Government advice. Use only containers sold as suitable for potable water, with a tight closure and a design that can be cleaned properly. Never repurpose a container that has held fuel, pesticides, bleach or another chemical, even if it has been washed.
If you choose this method, follow the container manufacturer’s cleaning instructions. The US Centers for Disease Control and Prevention’s emergency water guidance provides detailed cleaning advice and recommends dating home-filled containers, keeping them cool and dark, and replacing the water every six months. This is useful container-management guidance, although the UK Government’s simpler recommendation remains sealed bottled water.
Plan what the water will be used for
When the supply stops, allocate safe water in this order:
- Drinking and preventing dehydration.
- Infant feeding, medical equipment and other health needs.
- Taking medicines and preparing food that cannot be eaten safely without water.
- Handwashing, brushing teeth and limited cleaning of food-contact items.
Do not use drinking water for baths, showers, laundry or routine cleaning during a shortage. Keep food in the emergency cupboard that needs little or no water. Soap and water remain preferable for handwashing, but hand sanitiser and suitable wipes can reduce demand when water is very limited.
A water butt can provide useful non-drinking water for plants or, during an ordinary supply interruption, possibly for toilet flushing if the sewerage system is operating and local advice permits it. Do not count rainwater, water-butt water, floodwater, river water or decorative-pond water as part of the safe drinking reserve. A domestic filter jug does not turn an unknown or chemically contaminated source into safe drinking water.
What to do during a water outage or contamination incident
Check the water supplier’s website, messages and official local updates before using the tap. A loss of pressure, a boil-water notice, a do-not-drink notice and a do-not-use notice require different actions.
- No supply: use the stored reserve carefully and check where the supplier is providing bottled water or collection points.
- Boil-water notice: follow the notice exactly. The Drinking Water Inspectorate’s boil-water advice says to bring water to a rolling boil, let it cool naturally, store it in a clean container in the fridge and discard it if unused after 24 hours.
- Do-not-drink or do-not-use notice: do not assume that boiling or a household filter will solve the problem. Boiling can control many microbes, but it does not remove harmful chemical contamination. Use bottled water or the alternative supply specified by the authorities.
If someone in the household needs water for medical reasons, has limited mobility or would struggle to reach a collection point, register for your water provider’s support scheme before an incident. In England and Wales, the Consumer Council for Water explains free priority services, including emergency water support. Scottish Water operates a Priority Services Register, while Northern Ireland Water uses a Customer Care Register.
Emergency water storage checklist
- Count every person who normally stays in the home.
- Start with 9 litres per person for three days of drinking water.
- Build towards 30 litres per person for drinking, limited cooking and basic hygiene.
- Add separate allowances for babies, pets and medical requirements.
- Choose food that does not consume much of the reserve.
- Store sealed bottles or correctly prepared potable-water containers in a cool, dark place.
- Use a mix of container sizes that everyone can handle.
- Check labels, seals, leaks and dates twice a year, and rotate older stock into normal use.
- Write down the water supplier’s incident page and support details.
Emergency water resources
- GOV.UK Prepare water supply interruptions guidance gives current UK advice on quantities, bottled water, rainwater and actions during an outage.
- Drinking Water Inspectorate boil-water guidance explains which household uses require boiled water and how to cool and store it.
- NHS dehydration advice covers symptoms, higher-risk groups and when to seek urgent help.
- NHS guidance on making up baby formula explains why bottled water is not sterile and what to do when normal drinking water is unavailable.
- Consumer Council for Water priority-services guidance sets out the free extra help available to customers in England and Wales.
- Scottish Water’s Priority Services Register allows customers with additional needs to register for support during supply interruptions.
- Northern Ireland Water’s Customer Care Register provides free additional services for older people, people with serious medical conditions and others who need extra help.
- US CDC emergency water storage guidance provides detailed supplementary instructions for selecting, cleaning, dating and rotating refillable containers.
