Most people find it hard to believe that dishwashers generally use much less water than it takes to wash dishes by hand, but several studies have shown this to be true, including those done by the Waterwise organisation in the UK and the University of Bonn. Their findings were that while washing dishes by hand consumes between 67L and 103L of water per load, modern dishwashers (made after 1994) use between 15L and 22L per load. What is more, says Berry Everitt, CEO of the Chas Everitt International property group, using a dishwasher also saves power – it takes an average of 2,5kWh of water-heating energy to wash dishes by hand as opposed to the 1 to 2kWh of energy used by a dishwasher. He says the US Environmental Protection Agency (EPA) has calculated that installing a dishwasher can save you almost 19 000L of water a year and also result in a significant reduction of your electricity bill. “And as a bonus, you will also save some 230 hours of your time, because it takes much longer to wash, dry and put away dishes by hand than it does to load and unload a dishwasher.” However, he notes, to really generate the maximum savings from your dishwasher, the EPA recommends that you do the following:
Run your dishwasher with a full load. Half a load consumes the same amount of water and heating energy and is a waste.
Scrape don’t rinse: just scrape leftovers off dishes and load. Today’s dishwashers and detergents are designed to do the cleaning so you don’t have to pre-rinse in running water.
Turn down the temperature. Most of the energy used in a dishwasher is to heat the water and 49degC is quite hot enough to clean thoroughly and kill any bacteria.
Air dry your dishes. The heat-dry option on your dishwasher will consume a lot of energy so turn off this feature or stop the cycle and just open the door.