The company has improved its score from last year’s 63, which also saw it come last.
A spokesman for Thames Water said: “We are clearly not where we want to be, but have made major improvements over the past year towards getting our customer service and complaint handling in a much better place.
“Written complaints are down a third and customer satisfaction is up 12 per cent, one of the biggest improvements in the industry. We push forward from here in a strong position, fully committed to continue to improve customer service.”
The top company for customer service this year was water-only company South Staffordshire, with 89 points. Wessex Water topped the table for water-and-sewerage companies with 87 points to put it in joint second place overall in line with Anglian Water and Sembcorp Bournemouth.
Wessex Water’s director of customer and retail services Andy Pymer said: “We are delighted to retain our position as the top performing water and sewerage company for customer service.
“We continuously work hard to exceed customer expectations and on the few occasions where we don’t get it quite right we take necessary steps to learn from these so it doesn’t happen again.
The full results can be seen here.