Bank Holiday heatwave drives more than 1 billion litres of extra weekend water demand

Record-breaking heat drove more than 1 billion litres of extra water demand across London and the South East over the bank holiday weekend, with usage peaking on Monday as temperatures reached their highest point. 

The Met Office has confirmed the hottest May temperatures on record with 35.1°C recorded at Kew Gardens, as an exceptional early heatwave led to a sharp rise in water use across Thames Water’s region. In some areas, household water use increased by up to 50 per cent in homes with gardens.

Demand rose sharply across the weekend, with the biggest spike on Monday

·        Saturday +356 million litres

·        Sunday +302 million litres

·        Monday +387 million litres

Across the region:

·        London demand was consistently over 2,000 million litres a day, peaking at 2,140 million litres a day, a rise of 252 million litres

·        Thames Valley and Home Counties also saw a sustained rise in usage, reaching more than 740 million litres a day, which is an increase of 135 million litres 

That extra demand is enough to fill St Paul’s Cathedral around seven times over or provide drinking water for over 1.3m people for an entire year. 

This surge is being driven by peak outdoor use, including watering gardens, filling paddling pools and using hoses and sprinklers, often all at the same time.

Hot, dry conditions are also increasing pressure on the network, as the ground shifts and raises the risk of leaks. 

We are investing in the biggest upgrade to our network in 150 years, replacing and strengthening pipes and infrastructure to reduce leaks and improve resilience. At the same time, our teams are working around the clock to keep supplies flowing today, fixing hundreds of leaks every week, monitoring the network 24/7 and moving water to where it is needed most.

Simple steps can make the biggest difference

The biggest impact during heatwaves comes from reducing outdoor water use at peak times. Customers are encouraged to:

·        Swap hoses and sprinklers for a watering can

·        Avoid watering during the day and let lawns go golden

·        Keep a bowl or jug in your sink to catch water to reuse on plants

·        Use a bucket instead of a hose for tasks like car washing

Small changes across millions of homes can significantly reduce pressure on supplies during hot weather.

Notes to Editors

Unless specified, all figures are in comparison to May Bank Holiday weekend 2025