How long can a power cut last in the UK?

Most are fixed within a day. After Storm Arwen in November 2021, nearly 4,000 homes were without power for over a week and the last were reconnected after 13 days.

Does mobile signal work in a power cut?

Not always. Your phone may stop working if the local mast loses power, though some sites have backup power.

Bigger emergencies

A blackout longer than a week: what fails, and when

Short answerMost power cuts are fixed within a day. After Storm Arwen in 2021, though, thousands of homes waited more than a week. Heating and the fridge go first, then phones and internet as backup batteries run down, and in some areas mains water. Three days of supplies plus a plan for staying warm and fed covers most of it.

13days: how long the last homes waited for power after Storm Arwen in November 2021.

Last checked 28 October 2026. Based on Ofgem's Storm Arwen review, the government's E3C report, the National Risk Register and GOV.UK Be Ready.

It has already happened

Storm Arwen hit on 26 November 2021. Nearly a million homes lost power. Most were back within 24 hours, but more than 74,000 were off for over 48 hours, nearly 4,000 for over a week, and the last homes were reconnected after 13 days. The government's planning scenario for a failure of the national grid says full restoration could take up to 7 days.

What stops working, roughly in order

Straight away. Lights, most heating including gas boilers, electric cookers, and phones that run through broadband unless they have a backup battery. Why gas boilers stop.
After about 4 hours. The fridge warms up, even with the door shut. A full freezer lasts about 48 hours. Food in a power cut.
Hours to days. Mobile signal can fail if the local mast loses power. Some sites have backup power, but not all, and not for ever. Landline backup batteries last at least an hour.
Days. Mains water can be disrupted during and after a long power cut. After Storm Arwen, around 50,000 homes could have lost water from pumping stations without power. Generators and tankers cut that to about 2,000.
Longer. The government's scenario also names sewage, fuel supplies and card payments among the knock-on effects.

Getting through a long one

Water. Keep 3 litres per person per day for drinking. Use other water, such as rain from a butt, only for flushing toilets. Your plan works out how much for longer stretches.
Toilets. If toilets stop flushing, a bucket with a lid and strong bags works as an emergency toilet. Bag and seal the waste.
Warmth. Live in one room, close the curtains, wear layers and hats, and use sleeping bags. Never use a barbecue, camping stove or generator indoors.
Information. A battery or wind-up radio keeps you informed when phones are down. Call 105 for updates on the power cut, from any phone that works.
Extra help. Join the Priority Services Register now if anyone at home is older, disabled, has young children or relies on medical equipment. How to join.
Neighbours. Check on people living alone, especially older people and anyone who relies on medical equipment.

Sources