Dishwashers are one of the most efficient ways to clean dishes. A modern efficient dishwasher can use far less water and energy than washing the same dishes by hand. Because dishwashers use hot water, the type of dishwasher and how it’s used affect both water bills and energy bills.

Dishwasher technology

Most dishwashers are connected to the home’s hot water supply and also have a built-in heating element that raises the water temperature for cleaning and can heat the air to dry the dishes. A dishwasher’s hot water consumption and other technology features influence its operating costs.

Dishwashers and hot water

Dishwashers rely almost entirely on hot water to clean and sanitize dishes. According to the Water Research Foundation, the average US home uses more than 800 gallons of water per year for dishwashing, and nearly 100% of that water is hot water. Every gallon of hot water has two costs: the cost of the water itself and the cost of the energy needed to heat it.

Dishwashers versus washing by hand

Modern efficient dishwashers use between 1 and 4 gallons of water per load. Washing by hand often uses much more, since a typical kitchen faucet runs at about 2 gallons per minute. For example, washing a full load of dishes by hand with the faucet running for 10 minutes uses about 20 gallons of hot water, compared to about 3 gallons for an efficient dishwasher.

Dishwasher features

Newer dishwashers include several features that help save water and energy:

• Soil sensors detect how dirty the dishes are and adjust the amount of water and the length of the cycle.
• Eco or energy-saving cycles use less water and lower temperatures, often with a longer cycle time.
• Light cycles use less water for dishes that are only slightly dirty.
• Rinse-only cycles use a small amount of water to keep dirty dishes from drying out until there’s a full load.
• The option to turn off heated drying lets dishes air dry instead.

Dishwasher size also matters. Compact dishwashers hold fewer dishes, so they may need to run more often and can use more energy over time than standard-size models.

Upgrading your dishwasher

Upgrading from hand washing to a dishwasher, or from an older dishwasher to a new efficient model, can reduce water and energy use.

Energy efficiency certification

When shopping for a new dishwasher, it’s important to choose a model that has earned Energy Star certification in the US, or the highest energy efficiency rating in your country. A standard-size dishwasher is often the more efficient choice for households that fill it regularly, and countertop or compact dishwashers can be a good option for homes that regularly have few dirty dishes.

Smart daily habits

Small daily habits can help dishwashers clean efficiently.

Running full loads

According to Energy Star, dishwashers use about the same amount of water and energy regardless of how many dishes are inside. Waiting until the dishwasher is full before running it makes the most of every cycle, while taking care not to overcrowd dishes so water can reach every surface.

Scraping instead of rinsing

Rinsing dishes under the faucet before loading them adds to water and energy use. Scraping food scraps into the trash or compost is usually enough for a modern dishwasher to get dishes clean.

Choosing the right cycle

Using the eco or light cycle for everyday loads, and saving heavier cycles for very dirty pots and pans, can reduce water and energy use. Turning off heated drying and opening the door slightly at the end of the cycle lets dishes air dry.

Maintenance

Regular maintenance can help a dishwasher work efficiently:

• The filter, usually at the bottom of the dishwasher, should be cleaned regularly so water can flow freely.
• Spray arms should be checked for clogged holes from food particles or mineral buildup.
• The door seal should be clean and intact to prevent leaks.