WATER giants United Utilities have issued a warning not to take a dip in reservoirs during the hot weather.

Every year, swimmers succumb to the temptation to take a dip in the icy cold waters.

Nigel Fletcher, health and safety advisor, said: "Reservoirs seem inviting to swimmers, particularly on hot days after sunbathing, but cooling off in them can be deadly.

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

"Swimming in reservoirs is a highly dangerous activity.

"We sign our sites to alert people to the fact that swimming is not allowed.

"Adults and children alike should be aware of the perils.

"Reservoirs in use have water drawn from them through pipes under the surface and there are very strong undertows created as a result."