The Great Britain age group international produced a dominant display at the south Devon competition.
He finished nearly eight minutes ahead of his nearest rival in hot conditions.
Saunders was seventh out of the water, completing the 750m swim in 12.44 minutes.
He took the lead on the 24k bike ride and never looked back. He completed the cycle course in 49.07 minutes before completing the 6k run in 26.29 minutes, which was far quicker than anyone else.
His overall time was 1:29.36, with Neil Castree second in 1:37.33.