How to Green Your Dishwasher

So You Wanna Do More

Not content with just getting by? Go hardcore.

1. If you dishwasher is more than ten years old, it makes sense to chuck it (by donating it to a charity for reuse or recycling it for scrap metal, of course!) in favor of a new, efficient model. Today’s units use far less water and energy than older models, also saving you money on your utility bills.

2. Choose appliances that run on natural gas. This may not be possible in houses not piped for it, but typically natural gas appliances uses energy more efficiently than those that run on electricity.

3. A passive solar heating system can provide the hot water you need for your dishwasher, sparing the hot water heater. For more, see How to Green Your Heating.

4. Greywater captured from dishwashers can be used to water the garden and the lawn (but check your local laws for what's permissible). For more, see How to Green Your Water.

By the Numbers

Want the real deal? Here's where the rubber meets the road.

1. Replacing a 1994 dishwasher with a current model can save $25 in energy costs and 1,000 gallons of water annually. (link)

2. 80% of the energy used by dishwashers goes to heating the water. (link)

3. Using a fully-loaded dishwasher, without pre-rinsing, uses on average 35% less water than hand-washing all of those dishes. (link)

4. An Energy Star dishwasher can save up to $100 in water and electricity bills over its lifetime compared with a standard dishwasher. (link)

5. Running your dishwasher only when full could save up to 400 gallons a month. (link)

Getting Techie

Not content with the high level? Here's the nitty gritty.

1. The grunge match: Research conducted at the University of Bonn in Germany found that even the most frugal hand washer couldn’t compete with a modern dishwashing machine in efficiency. TreeHuger’s Christine Lepisto writes: “The Bonn study proves that the dishwasher uses only half the energy and one-sixth of the water, less soap too. Even the most sparing and careful washers could not beat the modern dishwasher.”

2. In the U.S., new appliances are sold with a yellow Energy Guide sticker that displays the unit’s energy consumption as well as the estimated operating cost per year. Here’s a link to how to use it.

3. "Smart” washers with dirt sensors were found by Consumer Reports to use “significantly more energy for heavily soiled loads than did nonsensor models.” This extra consumption is most often not reflected in the EnergyGuide sticker rating. Consumer Reports suggests skipping this fancy feature when shopping for a new machine.

4. Consumer Reports estimates that 80% of a dishwasher’s energy consumption is in the heating of water, both within the machine and in the home’s water heater. The other 20% is consumed by the motor and drying heater or fan. Of the models CS tested, washers used 31.5 to 12 gallons of water per load. They estimate that the annual cost of operation could range from “$25 to $67 with a gas water heater or $30 to $86 with an electric water heater.” (Consumer Reports)

5. Putting non-reusable containers like water bottles in the dishwasher, especially under heat, may cause them to break down and leach harmful chemicals. Be sure to put only dishwasher-safe items in the machine, especially if you plan to eat or drink from them. Also, you may want to seek out a dishwasher with a non-plastic interior for the same reason.

6. While phosphates are no longer permitted in laundry detergents in the U.S., they are still allowed in automatic dishwashing soaps (some states differ on the legally acceptable levels). Phosphates are additives that fight the effects of the minerals found in tap water--the minerals that cause hard water and the related spotting on dishes. Phosphates, however, also come from the same family of chemicals commonly used by farmers to fertilize crops. When phosphates wind up in waterways like rivers and coastal areas, they can “fertilize” algae populations, leading to large algal blooms which in turn can choke out plant and animal life in aquatic ecosystems. This is called eutrification, and along with agricultural runoff, can contribute to aquatic dead zones.