Are Dishwashers Environmentally Friendly?
Quick answer
Yes, in most cases. A full-size ENERGY STAR dishwasher uses about 3 to 3.5 gallons of water a cycle and around 240 kWh a year, which is far less water than washing the same load by hand under a running tap. Running full loads, skipping the pre-rinse and using air dry make the biggest difference.
A modern dishwasher is usually the greener option, mainly because it uses much less water than washing by hand. Most of a dishwasher’s energy goes into heating that water, so using less water saves energy too.
How much water and energy does a dishwasher use?
From the ENERGY STAR certified models in our data:
| Type | Water per cycle | Annual energy use | Cost per year at 18.31¢/kWh |
|---|---|---|---|
| Standard (24 in) | 2.3 to 3.2 gallons (median 3.2) | 200 to 240 kWh | about $37 to $44 |
| Compact (18 in) | 1 to 2 gallons | 80 to 155 kWh | about $15 to $28 |
The annual energy figure comes from the US Department of Energy test procedure, which assumes a set number of cycles a year, and includes the energy to heat the water. See how we calculate for the method, or compare models on our dishwasher running costs pages.
ENERGY STAR’s limit for a standard-size certified dishwasher is 3.5 gallons per cycle. Older dishwashers, especially those made before the federal standards tightened, use much more.
Is a dishwasher better than washing by hand?
Usually, yes. Washing a full load’s worth of dishes under a running tap can easily use several times the 3 to 4 gallons a dishwasher needs. ENERGY STAR estimates that using a certified dishwasher instead of washing by hand saves thousands of gallons of water a year.
Hand-washing can compete only if you are very frugal: one basin of hot soapy water, one basin of rinse water, and no running tap. Most people use more than that.
The comparison also depends on your water heater. If you wash by hand with hot water, that water was heated by your water heater, so hand washing is not “free” on energy either.
How to make your dishwasher greener
- Run full loads. The dishwasher uses about the same water and energy whether it is half-full or full. Load it fully but leave space for the spray to reach every item.
- Scrape, don’t rinse. Scrape food into the bin instead of pre-rinsing under the tap. Modern detergents and soil sensors are designed for unrinsed dishes, and pre-rinsing can use more water than the dishwasher itself.
- Use the eco or normal cycle. Heavy, sanitise and high-temperature options use more energy.
- Skip heated dry. Use air dry, or open the door a little at the end of the cycle and let the dishes dry naturally.
- Clean the filter. A clogged filter makes the dishwasher work harder and leaves dishes dirty, which leads to rewashing. Check your manual for how often.
- Buy ENERGY STAR when you replace it. Certified models are more efficient than the federal minimum.
What is the most eco-friendly dishwasher detergent?
There is no single best brand, and claims like “chemical-free” are meaningless, because every detergent is made of chemicals. Look instead for:
- The EPA Safer Choice label, which means each ingredient has been reviewed and is among the safest in its class for people and the environment.
- Phosphate-free formulas. Most US dishwasher detergents have been phosphate-free since the early 2010s, which reduces algae growth in waterways.
- Less packaging, such as cardboard boxes instead of plastic tubs, and water-soluble pods without a plastic outer wrapper.
Never put hand dish soap in a dishwasher. It makes far too many suds, which can leak out of the door.
Should you clean your dishwasher?
Yes. Clean the filter regularly and wipe the door seal. If you have hard water, a monthly empty cycle with a dishwasher cleaner or a cup of white vinegar on the top rack helps remove limescale and smells. Follow your manufacturer’s instructions, since some advise against vinegar on certain seals.