Police officers are including the Hogsmill river in their search for Tolworth pensioner John Harding, who has now been missing for more than 48 hours.
Mr Harding, 82, disappeared after leaving his home in Woodland Way, on the Sunray estate, on Saturday, April 26, at 7pm.
He is diabetic, and has dementia and high blood pressure.
Police have been in Tolworth today handing out flyers urging people to get in touch if they see Mr Harding.
Officers are including the Hogsmill, close to Mr Harding's home, in their search.
A Kingston police spokesman said: "The focus remains in the Tolworth area as this was where he is missing from.
"Obviously we're using all available resources to find John."
Mr Harding is five foot six inches tall, with short white hair and a mole on his forehead.
When last seen he was wearing a grey shirt, navy blue trousers and a brown three-quarter length coat.
Call police on 101 or Missing People on 116000, quoting reference 14MIS014040.