I didn't find any definitive answers online. But as these authors indicate, a lot depends upon whether you prewash dishes, the type of dishwasher, and how you wash dishes by hand. Using a heated dry cycle on the dishwasher would increase the electrical costs.
http://www.greenlivingtips.com/articles/211/1/Dishwashers-vs-hand-washing.html
http://forums.moneysavingexpert.com/showthread.html?t=372485
http://www.accessmylibrary.com/coms2/summary_0286-2084280_ITM
As a single person, I only run my dishwasher every 4 or 5 days. I'm sure that's cheaper than running water and using detergent to had wash them 2 or 3 times a day.
My father-in-law was an engineer who pioneered in dishwasher design for Hotpoint in the 1930s and 40s. He claimed that a dishwasher was more sanitary than handwashing. That makes sense because the machine uses much hotter water and is more thorough than a person can be washing the dishes by hand.
Is it cheaper to use the dishwasher or wash them by hand? I think dishwasher but I need some kind of proof. Ive read serveral times that im right but can someone confirm?
2 answers
A dishwasher uses more electricity. Modern ones use less water but when you wash dishes by hand, it's not necessary to let the water run. However, I agree it is more sanitary to use the dishwasher!
Sra
Sra