ICY water can kill. That's the message United Utilities is trying to get across to people during the summer holiday season.

Despite tragic drownings every year, swimmers are still tempted by the prospect of a cooling swim in a reservoir.

About 300 people drown in rivers, streams, lakes, reservoirs each year.

And, according to research by the Royal Society for the Prevention of Accidents, teenagers and young men are most at risk.

Peter Bradley, United Utilities health and safety adviser said: "Reservoirs do seem inviting to swimmers, particularly on hot days after sunbathing, but cooling off in them can be deadly.

"Additionally in the case of young men in particular, a few pints of beer can impair judgment, leading them to swim out until their bodies are suddenly gripped by the cold.

"In a reflex action, the body cuts the supply of blood to the arms and legs, preventing swimming and then people sink and drown."

Glynn Howarth, who works as a ranger for United Utilities in Lancashire, said: "It would be far better for people if they went down to their local swimming pool, rather than risking their lives swimming in reservoirs.

"We are not being kill-joys, we are asking people to protect themselves and their children."