A 15-year-old girl has become the 15th person to die in water-related incidents since the beginning of the heatwave - sparking new warnings over the danger of open swimming . More deaths have been reported this weekend after several days of warm, dry weather - though conditions are expected to cool significantly going into next week. It comes after police yesterday said a 15-year-old girl had died in hospital after getting into difficulties in the sea off the coast of Merseyside on Bank Holiday