Red hot temperatures - rising demand for water

‘Red Alert’ temperatures last week drove a significant increase in water demand across the Thames Water region.

The record-breaking heat and tropical nights led to higher water use by customers, with daily household water use increasing by an average of 30 per cent. 

Demand jumped sharply as temperatures rose above 30 degrees, with the biggest spike on Wednesday. In London, demand from Wednesday to Friday was consistently above 2,200 million litres a day.

In Thames Valley and the Home Counties, usage was over 750 million litres per day from Wednesday to Friday. The company supplied an additional 316 million litres in this area, for the week 20-28 June compared to the same period last year.

The company saw exceptionally high demand in Slough, Oxford, Swindon, Aylesbury and Wickham, putting increased pressure on the local network. To help maintain supplies for these areas the company asked customers to use water responsibly, only for essential needs until demand reduced.

Andrew Tucker, Water Demand Reduction Manager at Thames Water, said: 

“We saw a significant rise in demand across our region last week, particularly for outdoor water use.  Demand increased so sharply in some areas that people were using water faster than we could produce and move it through our network. We’d like to thank customers who played their part by reducing usage during this extreme weather, helping to keep supplies flowing while staying hydrated and safe.

“All our water is drinking-quality and comes from local sources, so small changes, such as using a watering can, reusing water and delaying non-essential outdoor jobs, can reduce what we need to take from the environment. We are asking customers to avoid using hosepipes and sprinklers on lawns and gardens so that supplies can be maintained for everyone during periods of exceptionally high demand.

“Our teams are working around the clock to keep water moving, fix leaks and maintain supplies. We’re also delivering our biggest infrastructure upgrade in 150 years and rolling out smart meters to help customers spot leaks and manage their water use.”

Company data from previous heatwaves revealed water use in homes with outdoor garden space can increase by 25–50% when temperatures reach 25 degrees or higher.

The hot, dry conditions also increased the risk of leaks across the network, as dry ground can cause pipes to shift. The company’s frontline teams worked around the clock during these extreme conditions to keep water flowing, fixing hundreds of leaks every week, monitoring the network 24/7 and moving water around the system to maintain supplies.

With temperatures forecast to rise again this weekend, Thames Water is continuing to ask customers to stay hydrated and safe while using water wisely, helping to give reservoirs and the network time to recover as the country moves through the summer.

New research by the company of 2,000 UK adults(1) found that nearly one in 10 people (nine per cent) use a lawn sprinkler during the summer months, despite a typical sprinkler using up to 166 litres of water every 10 minutes. In the Thames Water region, average water use is around 140 litres per person per day. The national target aims to reduce consumption to 122 litres per person per day by 2038.

Small steps to help save water now and during future heatwaves:

• Avoid watering gardens during the day and let lawns go golden – they recover fast
• Reuse water where possible, such as paddling pool water for plants
• Swap hoses or sprinklers for a watering can
• Fill paddling pools once and reuse rather than refilling
• Delay activities like car washing or use a bucket instead of a hose

Thames Water is delivering its biggest infrastructure upgrade in 150 years, replacing ageing pipes, reducing leakage and accelerating smart meter rollout across the Thames Valley. It has installed over 1.3 million smart meters, helping identify more than 135,000 customer-side leaks and recently partnered with Origin Tech to integrate its AI satellite leak detection system, Origin Orbit®, into regular operations.  

Notes to Editors

1. Research conducted by Opinium, amongst a representative sample of 2,000 UK adults (18+), data collected between 15-19 May 2026. Sample weighted to be nationally representative.