10 tips for making your dishwasher more efficient

Washing dishes uses water, energy, chemicals, as well as your valuable time, so an efficient approach can save a lot of each. There is still a debate which is greener, washing by hand or using a dishwasher, but if you do have a dishwasher or are thinking of getting one, here is some more in-depth knowledge to keep that dishwasher running green.

Top Green Dishwasher Tips


  1. Go for the full load
    Before running the dishwasher, wait until you have a full load (same rule of thumb for the clothes washer). This will help make the most of the energy, water, and detergent the machine uses. Loading the dishwasher efficiently helps.

  2. Choose your washer wisely
    Choose a dishwasher that is rated for energy and water efficiency. In the US, you can start by looking for Energy Star rated appliances, which use 25% less energy than the mandated minimum. Also, know how to read the yellow EnergyGuide sticker you'll find on all new dishwashers--as well as other appliances. Bonus featured include adjustable upper racks (so you can fit a wider variety of dishes), flatware slots (which keep your cutlery separated and easier to clean), and multiple cycle options,including half load cycles and eco cycles. Also look carefully at the decibel rating; cheap dishwashers can be really noisy and you don't want that in a small apartment. Spend a little more to get one with better insulation and as low a Db rating as you can afford.

  3. Join the clean plate club
    Go for dishwashing liquid and powder that is natural, biodegradable, and free of petroleum and phosphates. Also look for products sold in bulk to save on packaging. Powdered detergents are lighter and so require less energy to ship. For more, see How to green your cleaning routine. If you are running into spotting problems using phosphate-free detergents, try using a natural residue eliminator like Wave Jet.

  4. Skip the pre-rinse
    Most dishwashers today are powerful enough to get the all the gunk off, so a lot of pre-rinsing by hand is often just a waste of water and time. Plus, if you rinse all of the dirt off, your dog will have nothing to lick while you're throwing those plates in.

  5. Turn down the heat
    Most modern dishwashers have booster heaters to heat the water that comes from your home's water tank. Seems pretty redundant, right? Turning the water tank's thermostat down to 120 degrees results in additional energy savings without compromising on cleanliness.

  6. Air dry
    Instead of letting your washer use electric heat or a fan to dry the dishes, just open the door at the end of the washing cycle and let them air dry. Leave the dishes to dry overnight and they'll be ready for you when you wake up.Another option is moisture absorbing minreals, like the ones used in the Siemens Zeolith dishwasher. The minerals absorb heat during the wash cycle, and then release it during the dry cycle while absorbing moisture at the same time. They can reduce power consumption by 20 percent.

  7. Picking the right size
    Choose the size model that fits your needs. A compact model is more efficient than a large one unless you have to run it several times a day. For a single person, this might be just right.

  8. One glass fewer
    Using fewer dishes and utensils over the course of the day means doing fewer loads in the dishwasher, saving energy, water, and detergent.

  9. Keep those large appliances away from each other
    Putting your dishwasher next to your refrigerator will make the fridge have to work harder due to the heat coming off the washer.

  10. Off-peak washing
    Delay the start of your dishwasher for off-peak utility hours (many units have timers that will start the cycle at a programmed time). Some utilities even offer reduced rates for energy used during this period, and this is likely to become more and more common in the U.S.

This dishwasher uses almost no water at all! Photo by Dean Shareski/Flickr/CC BY 2.0

Green Dishwashing: By the Numbers


  • $40: Annual savings in energy costs you can realize by replacing a 1994 dishwasher with a current model, in addition to saving 1000 gallons of water.

  • 80 percent: Amount of energy used by dishwashers that goes to heating hot water.

  • 1000 gallons: Water saved each month by running your dishwasher only when it is full.

  • 280 million: therms of natural gas that would be saved by 2025 with energy efficient clothes and dishwashers. That amounts to heat 500,000 homes across the US.

  • 175 billion: gallons of water saved by 2025 with Energy Star rated appliances - enough to meet the water needs of 3 million people.

Sources: National Resources Defense Council, National Geographic, Alliance to Save Energy, Water - Use it Wisely

Chose a dishwasher size that fits with your lifestyle. Photo by Piotrus/Wikimedia/CC BY 2.0

Green Dishwashing: Getting Techie


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. TreeHugger'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."

Dirt Sensors costs you more
"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.

Gas vs. Electric Water Heaters
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)

Washing non-reusable containers
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.

Phosphates
Dishwasher detergents were the last product to include phosphates, which were really effective at removing stains and grease. However it cannot be removed from wastewater and was causing eutrophication, or algae blooms, whenever it got into fresh water. While phosphates have not been banned in all states, the manufacturers of dishwasher detergent have stopped using it. People have been complaining ever since that their dishwashers don't work as well, but the formulas for dishwasher detergent have been getting better every year.

Edited by Manon Verchot

Tags: Cleaning | Energy Star