And in the women's doubles, New Zealand sisters Georgina and Caroline Evers-Swindell passed Germany on the last stroke to defend their title.
Tufte put some indifferent form behind him to win in six minutes 59.83 seconds.
He rang me up and asked if he could come over and chat to me -I'm really pleased for him
Sir Steve Redgrave on Tufte
He moved away from Czech Ondrej Synek, with Kiwi triple world champion Mahe Drysdale trailing in third.
Drysdale, who has been ill this week, collapsed after crossing the finishing line.
Tufte thanked Great Britain's five-time gold medallist - and now BBC summariser - Sir Steve Redgrave for his help and advice.
"He has struggled with illness and, with my chequered history of illness, he rang me up and asked if he could come over and chat to me," Redgrave revealed.
"I'm really pleased for him."
Romanian women's pair Georgeta Andrunache and Viorica Susanu secured their second successive crown while China's late surge beat world champions Belarus.
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