Every Briton is being urged to stock up to nine litres of bottled water and three days' worth of food in new government guidance designed to ensure that households can survive a weather, cyber or other serious emergency.

The Be Ready campaign is aimed at persuading people to stock up supplies to last 72 hours, amid growing official concern about the impact of the climate crisis, technological dependancy and hostile state threats.

Dan Jarvis, the security minister, said that "those who can follow this advice should follow this advice". It amounted to "simple steps to be ready for everyday emergencies" as part of a wider, community-oriented effort "to improve our resilience as a nation", he said.

Wes Streeting, the defence secretary, added that Britain also needed to prepare for the threat of "state-sponsored terrorism" by Russia or other hostile powers targeting everyday infrastructure.

"Terms like hybrid warfare and grey zone threats do not accurately capture or convey to the general public what I prefer to describe as state-sponsored terrorism," he said. "So in the face of those threats, which are not hypothetical but real, and not somewhere else but increasingly here, we have to step up and take seriously our national resilience as well as our national defence. "It's really important that we ask households and businesses, are they prepared?

Are they ready? Do they know how they would respond in the event of everyday challenges that might manifest themselves?" People are advised to keep a ready supply of blankets and cash at home plus a first aid kit, a torch with batteries and a wind-up FM radio.

Three litres of water per person per day should be stored for drinking – and more is needed for cooking and washing, the guidance adds. The government had indicated in August that UK citizens would be told to stock up on tinned food but the Be Ready campaign from the Cabinet Office is more specific. It will be followed up with an advertising campaign on social media and radio.

Stocking up for three days is considered to be a realistic and practical proposal for households and would bring the UK in line with France, Ireland and the Netherlands in advising people how to be prepared for serious disruption.

Ministers timed the launch of the campaign to come before the winter storm season after a series of intense storms that have battered the UK in recent years. Tens of thousands of homes were left without power in the Midlands, the south-west and Wales after Storm Goretti hit in January, with winds reaching nearly 100mph.

There is also concern about the potential impact of the "super El-Nino", a global phenomenon that could lead to 2027 being the hottest year ever recorded and uncertain weather patterns, affecting global food supplies and energy systems.

The guidance emerged as 32 UK government websites were taken off line in a precautionary measure in response to the discovery of a security vulnerability in the PHP programming language used by millions of websites around the world.

Britain's National Cyber Security Centre sent out 50,000 alerts to affected organisations, in a reminder of the high degree of dependancy that modern societies have on the internet and other critical technologies.

Spain and Portugal were suddenly left without power for several hours in April 2025, in a cascading failure triggered by voltage instability in the network. About 55 million people were affected in the incident, the worst blackout in Europe in recent memory.

People also need to consider how to respond to hybrid warfare attacks by Russia or other hostile states, including cyber-attacks that could knock out payment systems used by businesses or cause supply chains to collapse, Streeting said.

The minister was speaking at a new tank gun barrel factory in Telford in the West Midlands The factory, owned by the German manufacturer Rheinmetall, is part of efforts to accelerate rearmament in the face of Russian military threats, but Streeting also emphasised that the public should be prepared for hybrid warfare, or sabotage actions that stop short of outright war.

Russian spy ships have been tracked by the Royal Navy monitoring undersea pipelines and cables that connect the UK to the continent of Europe and elsewhere, raising concerns they could one day be attacked, though this would represent a major escalation by Moscow.

European states have become increasingly vocal about the threat of sabotage efforts by enemies particularly Russia, which can cause disruption or even directly threaten safety. These efforts have included an explosives-laden drone found next to a Ukrainian cargo plane at Germany's Leipzig airport in August, and a series of explosions and fires at defence facilities.

Britain has only rarely embarked on public information campaigns, with governments of both parties reluctant to be accused of scaremongering. A 1980 campaign advising people on how to survive a nuclear war, Protect and Survive, advised people how to build a bomb shelter at home and retain enough food for 14 days.