The short answer is no. Surprised? Today’s dishwashers are extremely efficient, cleaning dishes to a sterile, sparkling shine with as few as nine litres of water. According to a study conducted at the University of Bonn in Germany, an energy-efficient dishwasher uses half the power, one-sixth the water and less soap to clean the same number of dishes as washing by hand.

But that only holds true for newer models. If your dishwasher is more than 20 years old, upgrading to a new, ENERGY STAR® model could save you more than $40 on your annual utility bill, and conserve more than 6,000 litres of water over the machine’s lifetime. Dishwasher technology has come a long way in the last two decades, with improvements such as electronic dirt sensors, finely tuned water-filtration systems, powerful jets and racks that position dishes for optimal cleaning. Many modern dishwashers also come equipped with booster heaters to maintain ideal water temperature for cleaning (60–62 C). This allows owners to turn down their homes’ water-heater thermostats.

To wash at peak efficiency, only run your machine when it’s full. Skip the pre-rinse (most modern dishwashers are powerful enough to clean without it), and whenever possible, use the energy-saver or “light wash” setting. Let dishes air-dry, instead of using heat dry. Finally, try not to install your dishwasher next to your refrigerator. The heat coming off the washer will force the fridge to work harder, drawing more power.

Make the switch

To save hot water when you shave, shut off the tap and rinse your razor in the sink. While you’re at it, try washing your hands and brushing your teeth using cold water only. If you cut hot-water waste in your daily routine by 5%, you’ll save around $21 a year (assuming you have an electric water heater).