When it comes to home energy hogs, washing dishes can be a surprising culprit. While dishwashers rank low on the list of appliances in terms of their electricity use, that position obscures a hidden cost: Water heating, essential to scrubbing success, is a home’s fourth highest electricity draw. That means when it comes down to cleaning dishes—by hand or by machine—the amount of water involved is the X factor.
Consumer Reports’ testing found that dishwashers typically use 3 to 6 gallons per cycle, which is less H2O than most handwashing scenarios. A University of Michigan study backs this up: It found that over a 10-year period, dishwashers used roughly half the water (16,300 vs. 34,200 gallons) and produced fewer emissions (2,090 vs. 5,620 kilograms of CO₂e) than scrubbing by hand.
Now, it should be said that two-basin washing—where you fill up one plugged sink with soapy water and another with rinse water—was found to be more efficient than even optimized dishwasher use. So, if you’re adamant in your adherence to sink-washing and have a double basin, that’s your best bet. But dishwashers are, on the whole, the most efficient option, because 73 % of U.S. households have one installed.
Any efficiency gains from using the dishwasher will go down the drain, however, if it doesn’t do its job well. Having to re-run it or hand wash afterwards means more water—and more energy and higher emissions. “A few small changes can make a big difference in how well they work and how long they last,” says Forrest Webber, founder of the home improvement resource The Trade Table. By understanding how your dishwasher operates and adopting some new habits, you can improve its performance and lower your energy bill in the process. Here’s how to get the most efficiency out of your dishwasher:
Don’t pre-rinse dishes
Skip the pre-rinse—it’s unnecessary and wastes water. Simply scrape leftover food into the trash or compost. Even if there’s caked-on gunk like dried peanut butter or egg yolk, let it lie. “Modern dishwashers and detergents are designed to handle a bit of grime,” says David Miloshev, an appliance repair technician and licensed electrician with Fantastic Services. Many machines include soil sensors, which measure how cloudy the water is to determine how dirty the load is. Pre-rinsing can confuse these sensors, causing the machine to run a shorter, less intense cycle—resulting in a finished load with still-dirty dishes. “Today’s machines actually perform better when there’s a little food left on the plates,” adds Webber.
Do run hot water before starting
Detergent typically needs hot water to break down and activate. “If the first fill isn’t hot, the detergent won’t activate properly, and the wash quality drops,” says Webber. A simple fix: Before starting the cycle, run the hot tap at the sink for a few seconds. This does use up a little extra hot water, but it pays off because it ensures the cycle starts steamy, boosting cleaning performance and efficiency.
Do load properly
Loading the dishwasher is, well, a loaded issue. It’s absolutely one of the most common household arguments—a battleground of routine, power, and stubborn logic (Although, we should note, these spats are probably not about the dishwasher). But, hey, per Webber and Miloshev, most people are loading it wrong. The biggest mistakes they see are overfilling racks and placing items directly in front of the detergent dispenser. This can disrupt the flow of water, block the release of detergent, reduce cleaning performance, and cause modern machines to run longer.
Here are a few things to remember:
General rules for loading the dishwasher:
- The top rack is the place for cups, glasses, mugs, and small-to-medium bowls, while the bottom rack is for plates, pans, pots, and heavier items.
- Don’t stack or overlap items. This can block the water spray and up the chances of chalky detergent residue on your dishes. “Think of it like setting up dominos for a water spray,” says Webber. “Everything needs a clear shot.”
- Don’t block the spray arms or the detergent door with oversized items like baking sheets or cutting boards.
Item-specific dishwasher loading tips:
- Plates should face inward toward the center spray arm
- Cups and bowls should be angled downward and toward the spray arm so water can reach all areas and drain properly
- Silverware should be placed in the designated basket or tray, with similar items like spoons separated to prevent them from nesting. Insert knives handle-up for safety and better cleaning.
Do run full loads
Cycle use the same amount of water and electricity, whether it’s fully packed or not. “Running a half-empty dishwasher is like boiling a full kettle for one cup of tea,” says Miloshev, “it’s a waste.” Unless your dishwasher has an efficient half-load or eco mode, wait until it’s full before turning it on.
Don’t overdo the detergent
Too much detergent can lead to residue buildup and cloudy glassware. “More soap doesn’t mean more clean,” echoes Miloshev. Both he and Webber recommend pairing your detergent with a rinse aid—especially if you have hard water areas—to prevent spots and mineral buildup. If you’re looking for a good option, we tested a variety of pre-portioned dishwasher tablets.
Do pick the correct cycle
Many people, per Miloshev, default to the “heavy” cycle, because it sounds more powerful and therefore better at getting the job done. But that’s usually overkill. High-intensity cycles are designed for extremely dirty dishes—those that are very greasy or caked with hardened messes—and can waste energy and water when used unnecessarily.
For most everyday loads, the “eco” mode is the best option. It uses cooler water and less water overall, and it runs longer to compensate—achieving similar cleaning performance while using up to 20% to 30% less energy, according to the DOE. Many people, per Miloshev, skip “eco” modes thinking that they’re not powerful enough. “Eco doesn’t mean weaker—it just means more efficient,” says Webber. Here’s a general breakdown of modes:
- Use “eco” modes for most loads—it’s the most efficient, even if it takes extra time.
- Use “normal” or auto” mode when you’re in a hurry or the dishes are a bit dirtier than usual. The soil sensor will help with efficiency.
- Use “heavy” modes for pots, pans, or dishes that are especially caked with crud
Don’t use heated dry
The heated dry function extends cycles by around 30 minutes and accounts for about 7% of a dishwasher’s overall energy use. Skip it. “Just open the door when the cycle ends,” suggests Miloshev. “Let the steam out, and the dishes will air dry just fine.” Pro tip: Tuck a clean kitchen towel into the door after the cycle is done to catch extra moisture.
Do clean the filter and spray arms
“If your filter’s clogged, your dishwasher’s running with one hand tied behind its back,” says Miloshev. Clean it once a month (it’s usually located under the spray arm and comes out with a counterclockwise twist). If dishes aren’t coming out squeaky, try cleaning the spray arm. “Even the smallest blockages in spray arms can reduce water pressure and stop detergent from reaching every surface.” Detach the spray arm according to your dishwasher’s instructions (or do a YouTube search if you don’t have ‘em) and give it a wipe with a water and vinegar mixture, making sure to clear any blockages into the small sprinkler holes.