United Utilities has booked an H1 pretax profit of £158.4m, down from £215.6m a year earlier.
The result was achieved on revenue of £853m, from £857m.
Interim dividend was 12.95p a share, up 1.1%.
The company said it was on track to meet its 2015-2020 totex and outcome delivery incentives targets.
"This has been a strong first half performance in which we made significant progress towards meeting our customer, environmental and financial targets," said CEO Steve Mogford.
"Customer service has again improved, resulting in our best score under Ofwat's revised service incentive mechanism. We're continuing to enhance our customer service offering and recently launched Priority Services, to provide dedicated support for those who are experiencing short or long-term personal or financial challenges.
"The acceleration of our capital investment programme continues to deliver early customer service and operational benefits. We have invested £383m in the first half of this year and remain on track to invest around £800m for the full year.
"Our Systems Thinking approach to running the business continues to drive innovation into our operations and we are rolling out further capability this year, including new process technology.
"Our environmental performance has remained consistently high and we were delighted to attain industry leading company status from the Environment Agency.
"Overall, we are encouraged by our progress in the early part of this regulatory period. We have a robust financial position and are confident that we can deliver our targets for both customers and shareholders."