How much water to store for an emergency

Water is the item GOV.UK lists first on its Be Ready checklist, and for good reason: it's the hardest thing to improvise. Most water interruptions are short and caused by things like maintenance or a burst main, but longer outages occasionally happen, and storms and power cuts can affect supply too.

The official figure

GOV.UK recommends 3 litres of drinking water per person per day for 3 days. The British Red Cross gives the range as around 2.5 to 3 litres. GOV.UK adds that you may need more to make up baby formula, for medical devices and for pets, and that more would be needed for tasks such as cooking and washing.

Litres are the GOV.UK figure (3 L × people × 3 days). The bottle split is our suggestion; 2 L bottles work too and are easier to carry.

Water for cooking and washing

Drinking water is the minimum. If you have space, it's worth keeping extra for washing hands, food preparation and basic hygiene. GOV.UK doesn't give a single figure for this. Our planning suggestion, which the calculator uses, is to aim for about 10 litres per person per day in total, so roughly 7 litres a day each on top of drinking water. For two adults over 3 days that's an extra 42 litres, or about three 20-litre food-grade containers. Tap water you fill yourself is fine for this.

Babies and pets

For babies, ready-made or ready-to-feed formula is the safest option in an outage, as you may not be able to boil water or sterilise bottles. GOV.UK explains that bottled water isn't usually recommended for formula, but in rare cases where tap water is unavailable you can use still bottled water with no more than 200 mg/L of sodium and 250 mg/L of sulphate, boiled and cooled for no more than 30 minutes. For pets, our estimate is around 60 ml per kg of body weight a day: about 1.2 litres for a 20 kg dog and 0.25 litres for a cat. Your vet knows best.

How to store it

• Bottled is simplest. GOV.UK calls bottled water the safest way to prepare. Sealed bottles keep well; check the date.
• Cool, dark and off the floor. A cupboard, under the stairs or under a bed works. Keep it away from sunlight and chemicals. (Our suggestion.)
• Rotate every six months. GOV.UK suggests checking your kit every six months. Use the older bottles and replace them.
• No space? GOV.UK says boiling or water purification tablets can help make other water safer to drink in an emergency. Tablets are sold at pharmacies, outdoor shops and online. Follow the label, and filter cloudy water first.
• Water butts are useful for flushing toilets and watering plants, but never for drinking.

If your water goes off

• Check your water company's website for updates and to see where you can collect bottled water.
• Use bottled water only for drinking, washing your hands and preparing food.
• Soft and fizzy drinks from the cupboard are also safe to drink.
• To wash hands, fill a clean washing-up bowl with water and add soap or household disinfectant, so the water lasts longer.
• Check on neighbours who might need help, and suggest the Priority Services Register. If you're on it, your water company will arrange alternative supplies for you.
• When supply returns, discoloured water is common. Run the cold tap nearest your stopcock (usually under the kitchen sink) for a while, and contact your water company if it doesn't clear.

Who is most at risk

GOV.UK highlights babies and young children, older adults, people with long-term health conditions and anyone who uses more water because of a medical condition. If someone at home relies on a medical device that needs water, talk to their care team about a plan.

Water is one part of the kit. See the full emergency kit checklist, or our Water Outage page.

Questions people ask