Thames Water has been criticised for its “massive, catastrophic failure” in the aftermath of the cold snap earlier this month, which “brought havoc” to the south of the London borough.
A cross-party committee urged the water company to improve the state of its water mains and response to emergency situations.
Hundreds of Streatham residents and businesses were left without running water for a few days and several schools were forced to close after burst mains caused supply disruptions.
Thames Water described the incident as “unprecedented” in scale and “technically complex” to resolve.
Around 50,000 customers across the capital were left without water following the extreme cold snap and subsequent rapid thaw, the company confirmed.
It is in the process of sending cheques to affected customers, following feedback from the “majority” of customers who said they would prefer cash compensation rather than a credit to their account.
Steve Robertson, chief executive of Thames Water, said: “I would like to personally apologise to all our customers across the region who experienced interruptions to their water supply following the freezing weather and rapid thaw in early March.
“Whilst we make extensive preparations for winter, this incident was unprecedented in terms of scale and technically complex to resolve. Our teams worked round the clock to restore supply however, we recognise we failed to protect our customers from the impact.”
Officials from Thames Water appeared before Lambeth Council’s overview and scrutiny committee last week.
In a letter to the committee, Thames outlined the work it had carried out to tackle the leak and the actions it had taken since the incident including its compensation scheme.
Councillor Jennifer Brathwaite, cabinet member for housing and environment, described Thames Water’s emergency procedures as “woefully lacking” and claimed vulnerable residents had been “put at risk”.
While Streatham Wells councillor Mohammed Seedat said residents had suffered similar problems at least three times in the last three years.
St Leonards Ward councillor Scott Ainslie told the Thames Water officials: “It’s no longer an excuse to say these were extraordinary weather situations; the old extraordinary is now the ordinary. You need to be preparing for this with the changes in climate – these shock weather systems are here to stay.”
Thames Water said it will respond in writing to the committee’s concerns and questions on incident response and long-term infrastructure investment.
Thames Water plans to compensate all affected customers by the end of April. It has agreed to pay customers “over and above the statutory minimum”. Those who experienced supply interruptions for four to 12 hours will receive £30, for 12-24 hours it will be £50, followed by £100 for 24-48 hours and finally £150 for anything more than 48 hours.
Ofwat is investigating water companies’ “preparedness” in the run up to the severe weather conditions to determine if they “planned ahead sufficiently”.
The regulator will publish its review conclusions by 15 June 2018.