How much water should you store?

Water is the first thing to store. Mains water in the UK is very reliable, but supplies can be interrupted by burst mains, flooding, drought, freezing weather or contamination. When it happens, bottled water in the shops can sell out quickly.

This guide explains how much to store, how to store it, and how to keep it fresh. If you just want a number, use our water storage calculator.

The short answer

For planning, we use 4 litres per person per day:

• about 3 litres for drinking
• about 1 litre for cooking and basic washing

Aim for 3 days to start with. For a household of four, that is 4 people × 4 litres × 3 days = 48 litres.

Where the figures come from

• The UK government’s Be Ready checklist uses 3 litres per person per day for drinking, and plans for 3 days. It notes you will need more for cooking and washing.
• US guidance from Ready.gov uses 1 US gallon per person per day for drinking and sanitation, for several days. One US gallon is about 3.8 litres.

Our 4-litre figure sits close to both. It is a planning assumption, not a medical recommendation.

Gallons: UK or US?

You will see gallons in some guidance, especially American sources. They are not the same:

Unit	Litres
1 UK (imperial) gallon	about 4.55 litres
1 US gallon	about 3.79 litres

So 48 litres is about 10.6 UK gallons or 12.7 US gallons. Our calculator shows litres first, with both kinds of gallon clearly labelled.

When to store more

Increase your store if any of these apply:

• Hot weather. People drink more in a heatwave. Add about 1 litre per person per day.
• Pregnancy or breastfeeding. Add about 1 litre a day for each person.
• Babies on formula. You need safe water to make up feeds. Follow the instructions on the formula packet.
• Illness. Fever, vomiting and diarrhoea all increase fluid needs.
• Pets. A medium dog might need around a litre a day, and a cat a quarter of a litre. Ask your vet if unsure.
• Hygiene. Washing hands, cleaning and keeping food preparation safe all use water. Allow an extra 2 litres per person per day if you can.

How to store water

Shop-bought bottled water

This is the simplest option. It is sealed, labelled and comes with a printed date. Keep it in its original packaging, somewhere cool and dark, and rotate it by using the oldest first.

Filling your own containers

Tap water stores well in the right containers:

1. Use food-grade containers made for drinking water. Never reuse containers that held chemicals, fuel, cleaning products or milk.
2. Clean the container and lid well before filling.
3. Fill from a cold kitchen tap that is connected directly to the mains.
4. Seal tightly and label with the date you filled it.
5. Store somewhere cool and dark, off the floor, away from chemicals, paint and fuel. Water containers can absorb smells.

Choosing container sizes

Smaller containers are easier to lift and pour, but you need more of them. A 25-litre container weighs about 25 kg when full, which is too heavy for many people to lift safely. A mix of 5 and 10-litre containers suits most homes.

Keeping it fresh

• Bottled water: replace by the date printed on the bottle.
• Water you filled yourself: replace every 6 months. Use the old water for plants or cleaning.

A simple way to remember: check your water store when the clocks change in spring and autumn.

If the water goes off

If your water supply is interrupted:

• Check your water company’s website or social media for updates.
• If you are on the Priority Services Register, your water company may be able to deliver bottled water.
• Use your stored water for drinking and food first, and less important uses last.
• If you are told the water may be unsafe, follow your water company’s advice. Our guide to emergency water purification explains boiling, filters and tablets.

Water storage checklist

• Work out your total with the water calculator
• Store 3 days of water for everyone, including pets
• Use food-grade containers and label them with the date
• Keep containers cool, dark and away from chemicals
• Put a reminder in your calendar to rotate water every 6 months
• Have a way to treat water if you are unsure it is safe

Sources and further reading

• Be ready for emergencies (includes the Be Ready checklist) (UK Government)
• Water (Ready.gov (US Government))
• Priority Services Register (The PSR)