Which conserves more water? Well, one must take many factors into account.
Unfortunately I do not have the luxury of using a dishwater in my current apartment, although when I did have one, it was used more as a storage device for dirty dishes. I would put everything in the dishwasher and once I had time to begin my cleaning routine (I’m a bit OCD when it comes to cleaning–hence the cleaning “routine”) I would take the items that could not be washed out (wooden spoons, bamboo cutting board, knives) and hand wash them while staying conservative of my water usage.
But before we can determine which is method is more efficient and eco-friendly, according to recycling.com, we must first look at a few factors.
MACHINE WASHING: What goes into making a dishwasher? Is your dishwasher made from recycled parts? Was it produced in a sustainable manner? Can your dishwasher be recycled when you are finished with it, or when it is broken beyond repair? (Here is a good resource to help you find a place to recycle an old dishwasher.)
HAND WASHING: Requires hands, water, soap and a sink. Simple.
MACHINE WASHING: First, find out how old your dishwasher is. As a general rule, the older the model, the more water it uses.
The EPA’s water trivia facts (updated in 2007) claims that hand washers use 9 to 20 gallons of water while the average dishwasher uses 9 to 12 gallons of water. Judging by the fact that Energy Star dishwashers must use 5.8 gallons of water or less per cycle to receive certification, these numbers seem fairly accurate. But, since hand washers can have such different ways of washing, it is hard to estimate this figure.
HAND WASHING: The most proficient way to hand wash dishes is by filling your sink with soapy warm water, soaking the dishes and either using a second sink (or bucket/large bowl) with cold water to rinse the dishes. You can use a drying rack, wipe dishes dry or use your dishwasher as a drying rack.
While hand washing dishes requires energy if you are using hot water, running a dishwasher uses energy to operate and to heat water. To use less energy to heat water, lower your water heater’s temperature a few degrees.
According to the U.S. Department of Energy, average dishwashers use about 650 kWh (kilowatt hours) per year or an estimate of 0.558 kWh during each cycle. If you run your dishwasher every other day (about 182 times a year), that’s about 102 kWh per year.
CONCLUSION: Each case is different, but hand washing while keeping the water running is clearly going to use more water than a dishwasher. If you are conservative and wash dishes in a sink full of soapy water, you could be using less water than your dishwasher. Many factors must be taken into consideration when clearing determining between the two options, including how often you’re washing dishes by hand, whether you pre-rinse dishes before loading them into the dishwasher, whether you’re running a full load, whether your dishwasher itself is sustainable (or more so than most) and whether you are using the heated dry option on your dishwasher. The hand washing versus dishwashing feud cannot be answered in terms of black and white.
Although comparing hand washing and dishwashing is difficult, I am sure we can agree on several things to stay more efficient and more eco-friendly. If you do use the dishwasher, make sure you always run a full load, skip the heated dry option and air dry dishes, refrain from needless pre-rinsing and try to upgrade to a more efficient model (if you have not already). Just try and use less. Try using fewer items in general, such as reusing your cups throughout the day or wiping breadcrumbs off the plate that only carried a sandwich and popping it back in the cabinet.