Underlying pretax profit fell 5 percent to 185 million pounds, falling short of estimates of 199.4 million pounds, according to a Thomson Reuters I/B/E/S poll.
Infrastructure renewals expenditure rose 38 percent to 66.4 million pounds, the company said, offsetting a 4.5 percent regulated price increase.
United Utilities, however, said it expects to deliver a good underlying financial performance over the remainder of the year, and added it was on track for up to 700 million pounds of capital investments for the year.
Shares in United Utilities closed at 610 pence on Tuesday, valuing the business at nearly 4.20 billion pounds.
(Reporting by Adveith Nair; Editing by Kate Holton)