If domestic dishwashers are connected to the cold as directed by the manufacturer. And people use cold water washing powder in much larger quantities than hot water powder, why create a dual system in a domestic situation when Legionella is killed in the hot water system??
Homeowner, both tanks should be at greater than 66c to ensure no growth of legionella. (bet I’m a degree out, and get bitten for it
All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia