When it comes to long-standing green-living debates, washing dishes by hand versus using an automatic dishwasher is right up there with hand-driers versus paper towels. Here are some carbon-footprint figures, which hopefully will resolve the issue for once and for all.

Almost zero CO2e: by washing dishes with hand using cold water (but the plates aren't clean)
540g CO2e: washing dishes by hand, using water sparingly and not too hot
770g CO2e: in an automatic dishwasher at 55°C
990g CO2e: in a dishwasher at 65°C
8000g CO2e: washing dishes by hand, with extravagant use of water

Source: How bad are Bananas? The carbon footprint of everything by Mike Berners-Lee

The Bonn University* identified that majority of households are not careful when it comes to using water when washing dishes – especially as many people wash dishes by hand, under a running tap. The evidence shows that a dishwasher can on average save a lot of water when used properly.

How can dishwashers be a greener option?

Most automatic dishwashers manufactured since 1994 use less water per cycle than the equivalent required to washing dishes by hand, because they recycle the water throughout the wash. Newer models heat only the amount of water they need - and being cold fill, the water is heated in the dishwasher itself, not in the household's hot water tank or central heating system, where heat gets lost in transit. A standard 60cm wide household dishwasher is designed to hold 12 or 14 place settings. This water and energy efficiency can also help lower your utility bills.