Emergency water storage (UK): how much to keep and how to store it

Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Updated 25 October 2026 and checked against the government's Be Ready checklist.

For an emergency in the UK, store at least 3 litres of drinking water per person per day for 3 days, so 9 litres each, as the government's Be Ready checklist advises, with more for cooking and washing. Sealed bottled water is the simplest option. You can also fill clean, food-grade containers with tap water from the kitchen cold tap, seal and date them, keep them somewhere cool and dark, and replace them every six months.

Water is the part of an emergency kit most people forget and the part that runs out first. The Be Ready campaign, launched on 22 October 2026, puts it at the top of the checklist. For the rest of the kit, see our home emergency kit checklist.

Why I wrote this guide. My work is in food for people far from a kitchen, and in endurance and expedition settings water shapes every other decision: what you can eat, what you can carry and how far you can go. The same is true at home when the taps stop. This guide covers how much to store, how to store it safely, and how to make your food choices save water rather than use it.

How much water to store for an emergency

Be Ready asks for 3 litres per person per day for drinking. The old government Prepare website allowed about 10 litres per person per day for drinking, basic cooking and washing, which is a sensible target if you have the space.

• One adult, 3 days: 9 litres for drinking.
• Two adults: 18 litres, or nine 2-litre bottles.
• A family of four: 36 litres, or eighteen 2-litre bottles.
• Pets: a common rule of thumb for dogs is about 50ml per kg of body weight a day, so around 3 litres for 3 days for a 20kg dog.
• One week, one adult: 21 litres to drink, or around 70 litres if you also cook and wash with it.

Allow more in hot weather, for anyone who is unwell, and for babies who need formula made up. Water weighs 1kg a litre, so 36 litres is 36kg: spread it across the house rather than stacking it in one place.

Bottled water or stored tap water?

• Bottled water is sealed, portable and easy to rotate. Its best before date is mainly about taste and quality, so keep it in date, store it out of the sun and away from strong smells, and use it up in everyday life before it expires.
• Stored tap water costs almost nothing. UK mains water contains a small amount of chlorine that helps it keep, and in clean, sealed containers stored cool and dark it is commonly recommended to replace it every six months.

Most households do best with a mix: bottled water in the kit and a few larger containers of tap water filled at home.

The best containers for storing water

• Food-grade plastic made for drinking water, such as water carriers and jerry cans marked HDPE (recycling code 2), or PET bottles (code 1).
• Stainless steel or glass, though glass is heavy and breakable.
• Sizes from 5 to 25 litres are easier to lift, carry and fit in cupboards than one big tank. A carrier with a tap makes pouring easier.
• Never use containers that have held anything other than food or drink, such as chemicals, fuel or cleaning products.
• Avoid old milk bottles. They are hard to clean properly and the thin plastic is not made to last.
• Opaque containers, or ones kept in a dark cupboard, stop light encouraging algae.

How to store tap water safely, step by step

• Wash the container and lid in hot, soapy water and rinse well. You can sterilise it with a baby-bottle sterilising solution, following the instructions on the pack.
• Fill it from the kitchen cold tap. In many UK homes this is the tap fed directly from the mains, while other taps may be fed from a storage tank in the loft, which is not meant for drinking.
• Fill to the top, seal tightly and write the date on a label.
• Store it somewhere cool, dark and clean, off the floor, and away from chemicals, paint and fuel.
• Replace it every six months. A good habit is to swap it when you check the rest of your kit.

If you freeze water in bottles, leave a gap at the top so they do not split. Frozen bottles also help keep a freezer cold for longer in a power cut.

Where to store emergency water at home

• Under the stairs, at the bottom of wardrobes, under beds and in kitchen cupboards.
• Not in direct sun, not next to the boiler, and not beside chemicals or anything with a strong smell.
• Garages, sheds and lofts get hot in summer and can freeze in winter, so they are a poor choice for drinking water.
• Keep a few small bottles where you can grab them for a grab bag or the car.

Water already in your home

If supplies are interrupted, there is often more water in the house than you think:

• Fill the kettle, a few large pans and the bath as soon as an interruption is announced. Use bath water for flushing toilets and washing, not for drinking.
• If you have a hot water cylinder or a loft tank, that water is better kept for washing and flushing than drinking.
• Ice and frozen bottles in the freezer can be melted for drinking.

What to do in a water outage

• Check your water company's website and social media for updates and the location of any bottled water stations.
• If anyone in your home needs extra support, join the Priority Services Register, which tells your water company you need extra help during an interruption.
• Use stored water in order of priority: drinking first, then food, then hygiene.
• Check on neighbours, especially anyone older or living alone.
• When supply returns, run the kitchen cold tap until the water is clear before drinking it.

How to make water safe to drink

If you are told to boil water, or you are unsure of a source, there are three main options:

• Boiling: bring water to a rolling boil and let it cool before drinking. This is the method UK water companies use in boil water notices.
• Water purification tablets: light and cheap, and useful in a grab bag. Follow the instructions for dose and waiting time, which vary by brand.
• Portable filters: useful outdoors, but check what each one removes, as not all filters deal with every kind of contamination.

If your water company issues a notice, follow its instructions over any general advice.

Choose food that saves water

Your food choices decide how far your water goes. Dry rice, pasta and freeze-dried meals all need water to cook, while tinned food and ready-to-eat food need none, and tins in juice or brine add fluid. In a water outage, build meals from no-cook food: tinned fish and beans, oatcakes, nut butter, nuts, dried fruit and dense bars. Our 3-day emergency food supply list uses only food that needs no cooking, and our guide to emergency rations compares long-life options. Go easy on very salty food, because it makes you thirstier.

Common questions about storing water

How much water should I store for an emergency in the UK?

At least 3 litres per person per day for 3 days, so 9 litres each for drinking, with more for cooking and washing if you have the space. A family of four needs 36 litres to drink.

How long can you store tap water in plastic bottles?

In clean, sealed, food-grade bottles kept somewhere cool and dark, the common advice is to replace stored tap water every six months. Label each container with the date you filled it.

Does bottled water go off?

Sealed bottled water carries a best before date, which is mainly about taste and quality rather than safety. Store it away from sunlight and strong smells, and rotate it into everyday use before the date.

Can I store water in old milk bottles?

It is best not to. They are hard to clean thoroughly and the plastic is not designed to last. Use proper food-grade water containers or bottles that held drinking water.

Can you drink water from the hot water tank?

It is better used for washing and flushing. Keep your stored bottled or tap water for drinking, and boil any water you are unsure of.

Is it OK to store water in the garage?

Garages get hot in summer and can freeze in winter, and often hold fuel and chemicals. A cool cupboard inside the house is a better place for drinking water.

Sources: GOV.UK Be Ready, be ready for emergencies; Be Ready checklist (PDF); British Red Cross, prepare an emergency kit; Priority Services Register.