Wednesday, April 7, 2010

Is It Better To Use A Dishwasher Or Wash Dishes By Hand? (via “Science Man”)

We were tipped off to Seventh Generation’s Science Man recently by @WorldCentric.
The Science Man is 7th Generation’s Director of Product
 & Environmental Technology, Martin Wolf, who has 30+ years in environmental product design, evaluation, and analysis (true to name, he also has a pretty fantastic Wolf man ‘stache & beard). He takes eco-related questions from the general public and answers them quite well (with full references).
In a recent question, “Earthy09″ asked the Science Man:

How much water and total energy does the average dishwasher use? Is using a dishwasher more sustainable than washing dishes by hand?

His answer:
“According to the U.S. Department of Energy, washing your dishes by hand uses more than twice the amount of energy and water it takes to run an EnergyStar dishwasher when washing full loads. By using an energy efficient dishwasher instead of washing dishes by hand you’re saving money and time too!
That said, a lot depends on how you wash your dishes! Most people let the water run continuously as they wash their dishes. If you do this, dishwashers win hands down. However, if you fill a dishpan with water and only run the water to rinse dishes after you have washed all of them, then you can be more water and energy efficient than a dishwasher. The average water consumption of a conventional dishwasher is 6 gallons per cycle, while an energy efficient dishwasher uses 4 gallons per cycle.”
See Full Response for energy numbers
4 gallons! Kitchen faucets flow at at bare minimum 1.5 gallons / minute (most are 2 – 3.5 gallons / minute). So, if you’re running your tap >3 minutes (which you almost certainly are are if you’re washing a full load of dishes), then the dishwasher is clearly the way to go.
So there you go.
Keep your eyes peeled for more posts from us down the road highlighting other Science Man answers (e.g., “Are plastic shower curtains bad for the environment of your home?”).