How Much Water Should a UK Household Store?

Do the simple calculation first

Take the number of people in the household, multiply by the number of days you want to cover, then multiply by 2.5 to 3 litres. That gives a minimum drinking-water range. Four people for three days is 30 to 36 litres. Two people for seven days is 35 to 42 litres.

That figure is drinking water only. The Government Prepare guidance notes that around 10 litres per person per day is more comfortable because it allows some water for cooking and basic hygiene. You do not have to store the comfortable figure on day one. It is a useful long-term target if space allows.

Use stored water before you reach for a filter

A sealed bottle is predictable. You know where it came from and it is ready to drink. That is why storage should be the first line of defence. The current Prepare guidance specifically recommends purchased bottled water rather than filling long-term drinking-water stores from the tap yourself.

Filters and purification tablets are still useful, but only as backup tools. Different products remove different contaminants, and no compact filter makes every possible water source safe. During a real incident, follow your water company and public-health advice.

Separate drinking water from utility water

If you have room, keep drinking water separate from water intended for toilet flushing or cleaning. A rain butt can help with non-drinking uses, but Government guidance warns that collected rainwater can contain bacteria or disease and should not be treated as drinking water by default.

Label containers clearly. In a stressful outage, a simple label avoids somebody using your clean drinking reserve to flush a toilet.

Plan for the people who need more

Babies, pets, people with some medical conditions and people using water-dependent medical equipment may need more than the basic calculation. Ready-to-feed baby formula can also reduce dependence on boiling water when normal services are disrupted.

People eligible for a water company Priority Services Register should consider joining before an outage happens. Your water provider is the main source of local information during an interruption.

Storage is boring, which is why it works

Water preparedness does not need to be complicated. Put a modest sealed reserve somewhere cool and out of direct sunlight, know how much you actually have, and review it periodically. Add portable containers, filtration and treatment only after the basic stored supply is covered.

Useful kit for this plan

Gear should support the plan, not replace it. These are relevant items from the main catalogue. Check the current listing and specification before buying.

Sources checked for this guide

We use public sources for the factual backbone and write the guide in our own words. Source pages can change, so the links below are the place to check current official advice.

Editorial review date: 17 September 2026. If an official source conflicts with this page, follow the official source.