Flooding in Hampstead and NW3: A Timeline, 1975 to Today

North West London does not look like flood country. Hampstead sits on the highest ground in inner London, and the streets around it are leafy and quiet. Yet this corner of the city has seen some of the most intense rainfall ever recorded in Britain, and in the last few years it has flooded again and again. This is a dated record of the main events, with a source for every one, and what each means for the homes we work in.

Worth knowing: Most flooding here is not rivers bursting their banks. It is rain falling faster than old drains can carry it away, and water mains failing under the street.

14 August 1975: the Hampstead Storm

A thunderstorm stalled over Hampstead and dropped about 169mm of rain in a little under three hours, one of the most intense downpours ever measured in the UK. Basements flooded, roads turned into rivers and Tube lines were affected. It remains the benchmark against which every local storm is measured.

What it means today: a once-in-a-lifetime storm can happen here. Homes below street level need a plan for water coming in.

2002: the storm that led to a new sewer

After severe flooding in 2002, a large storage sewer was built under Sumatra Road in West Hampstead to hold storm water until the system can cope. It helps, but it was not designed for the kind of rain that fell in 2021.

12 July 2021: the flash flood

A storm that Thames Water described as a “one in 179 year” event flooded more than 100 homes across Camden. Goldhurst Terrace, Fairhazel Gardens, Belsize Road and Priory Road in South Hampstead were among the worst hit. In West Hampstead, West End Lane near the fire station became a river and residents reported sewage coming up through their toilets. Camden published a formal investigation into the flooding in July 2022.

What it means today: combined Victorian sewers can push sewage back into homes. A non-return valve on your drain is the main defence.

25 July 2021: Hampstead floods again

Less than two weeks later, a second downpour flooded South End Green and parts of Hampstead. Back-to-back events like this are why residents’ groups now campaign for better drainage and flood insurance.

17 December 2022: the Belsize Road main burst

In the early hours, a 42-inch water main and a 15-inch main burst on Belsize Road. The London Fire Brigade reported flooding around 50cm deep across an area of about 800 metres. Around 100 properties were affected, and firefighters used boats to help people to safety. Thousands of homes lost water or pressure for days, a week before Christmas.

What it means today: not every flood comes from the sky. A burst main can fill a street in minutes, and basement flats take the worst of it.

Why this part of London floods

Hampstead sits on London Clay, with sandier layers above that feed natural springs, the sources of the old Fleet, Tyburn and Westbourne rivers. When rain falls hard on the high ground, it runs downhill fast and gathers in the lower streets. Most of the area’s sewers date from the Victorian era and carry rainwater and sewage in the same pipes. In a cloudburst, they fill and back up.

Protecting a home here

• Know where your stopcock and fuse board are, and make sure both are easy to reach.
• Fit a non-return valve on drains in basement and lower ground floor flats.
• Keep valuables and electrics off the floor in rooms below street level.
• Check your insurance covers flood and sewage damage, not just escape of water.
• Watch Met Office weather warnings for thunderstorms and heavy rain, and keep the number of a plumber who can come out at night.

If water is coming into your home now, call 07862 142953. Our guide to a blocked toilet or drain explains what to do when sewage backs up.