Severn Trent has lifted its H1 pretax profit to £185.0m, from £175.3m.
Turnover was £906.8m, from £878.6m.
Interim dividend was 32.6p a share, in line with policy.
CEO Liv Garfield said:
"Our strategy of keeping our customers at the heart of the business and investing for the long-term is driving clear results.
"We remain committed to being the most trusted water company by 2020, by striving to provide outstanding customer experience, best-value service and environmental leadership.
"We are focused on the things that matter most to our customers while also maintaining the lowest bills in Britain. External sewer floodings are down 9% year-on-year, and we have almost trebled the number of vulnerable customers supported.
"We are also proud of our performance on customer complaints, achieving the largest reduction in complaints in 2015/16 of all water and sewerage companies, as measured by the Consumer Council for Water, giving us the second best performance overall.
"Investing for the long-term in our network and skills is vital. As custodians of a totex investment programme of over £6 billion this regulatory period, we have made strong progress on our biggest ever capital project, the Birmingham Resilience Programme.
"We are doing more for our communities and have also more than doubled the number of apprentices and graduates hired into the business. We have committed to reinvest £120 million of our totex efficiencies into three important areas for our customers; water quality, security and vulnerable customers.
"While we are encouraged by the results of everyone's hard work, we are aware that much remains to be done to achieve the high standards we set ourselves and continue to deliver for all stakeholders."