Homes in more than 50 postcodes across west and southwest London had low pressure or no water on Wednesday morning after the power outage at Thames Water’s Ashford water treatment works.
Temporary water bottle stations were set up for residents, tankers drafted in to help hospitals and more than a dozen schools closed, forcing frustrated parents to take time off work.
Thousands of customers in Twickenham, Putney, Richmond and Hampton were among those affected.
While most residents had their water supply returned to normal by Wednesday evening, some have reported having no water for a second day.
A Thames Water spokesperson said: “Customers across West London should now have their water back on following problems at our nearby water treatment works yesterday.
“We’re sorry to customers who are still experiencing low pressure or no water. This is likely caused by airlocks in our pipes.
“We have plumbers on standby to support customers and would encourage anyone experiencing supply issues to give us a call on 0800 316 9800.”
Issues at the Ashford water treatment works had a knock-on effect at the Hampton plant - one of Thames Water’s biggest operation sites - affecting a large number of families in the area.
Mayor of London Sadiq Khan said he would find out what caused the power supply issue and “how to make sure it does not happen again”.
In an update on Wednesday, Thames Water said it is making “increased checks” at its water treatment works and “working with power distributors to understand the cause of the problem and reduce the chances of it happening again”.
Liberal Democrat Assembly Member Hina Bokhari said some schools didn’t need to close and said “last minute school closures and hospital disruption like this is not acceptable”.
Yesterday, I had the opportunity to challenge @thameswater about power supply issues that impacted many in South West London yesterday morning. Last minute school closures and hospital disruption like this is not acceptable. pic.twitter.com/n2du1ZcEQg
— Cllr Hina Bokhari AM 🔶 (@HinaBokhariLD) September 14, 2023
Thames Water interim CEO Cathryn Ross said: “I do want to offer my apologies on behalf of Thames for the disruption.”