Dishwashers versus Hand-washing

Dirty dishes in sink

It's time to wash up! But should you be using machine power or man power for the chore?

Credit: iStockphoto

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Testing hand-washers

But how do dishwashing machines stack up compared to washing by hand?

Bonn University's household and appliance technology professor, Rainer Stamminger, analysed the best dishwashers manufactured between 2002 and 2004.

He rated the efficiency of two machines washing 12 place settings (140 pieces). To account for a variety of dish-washing styles, Stamminger managed to convince 113 hand-washers to chain themselves to a sink.

Europe's best machines only used around 15 L and consumed between one kilowatt-hour (for a standard cycle) and two kilowatt-hours (intensive cycle) of energy to wash and dry the dishes.

The hand-washers, meanwhile, averaged a whopping 103 L, with one enthusiastic scrubber using 447 L!

However it should be noted that among the various hand-washing styles, the more common 'dishwashing economisers' used as little as 30 L of water.

Energy used by hand-washers started below the same amount of energy used by dishwashers on standard cycle. But more profligate hand-washers used up to 8 times this amount.

According to Stamminger's cleanliness scale, the dishwashing machines, on average, beat the hand-washers.

The verdict

Properly stacked dishwashers use less water and are usually better on the electrical energy front compared to hand-washing.

But there are some general tips for reducing impact either way.

Always scrape your plates into the bin with a knife or fork, and avoid pre-rinsing under a running tap.

If washing by hand, use two sinks - one full of hot, sudsy water for washing, and one filled with cold water for rinsing.

For dishwashers, make sure the machine is always full before you press 'go'.

Clean the filter regularly for increased efficiency, and, if you can, bypass the drying phase by opening the door to let out air while the dishes are hot - you'll be surprised how quickly they dry.

If you're in the market for a new dishwasher, shop by the stars.

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