This argument has been raging since dishwashers became standard kitchen equipment. The manufacturers of dishwashers claimed from the beginning that their appliances were more than just a labor-saving device. They claimed that using a dishwasher would save you money in water and energy costs.
In recent years, studies came out on the side of hand dishwashing as the best option, mainly from an environmental point of view. It was shown in several studies that you could actually save on both water and energy for heating the water, by doing the dishes the old way, by hand.
While the debate never really went away, new studies in Europe are showing that there are so many variables that it isn’t a cut and dried argument at all. Lots of complicated figures and confusing formulas are used that it can be a bit hard to decipher.
So I thought I’d put it into language that everyone can understand so you can make up your own mind as to which method, of getting the dirty dishes clean, is the greenest and most cost-effective.
Firstly, it does seem that the numerous variables make it very hard to make a fair comparison. It all depends on – the model and age of the dishwasher (the automatic one, not the human one); by what means the water is heated in the home; how the task of hand washing is performed; the frequency of the dishwashing. Each of these factors could change the result as far as environmental and cash savings.
From an environmental perspective, it is the carbon footprint of the process that is important. From a money saving perspective, it is how much water and energy are used for each method. For the sake of the exercise, it is assumed that the same amount of dishes are washed by each method, this being the eight place settings plus 6 serving/preparation dishes that the standard automatic dishwasher holds.
Water: an average dishwasher with no Energy Star Rating uses 6 gallons for each cycle while one with an Energy Star Rating uses just 4 gallons.
To equal this, the hand dishwasher would need to be able to rinse as well as wash the same number of pieces – 54 in all – in 2 minutes worth of water. This is based on the statistic that the average household faucet runs at a rate of 2 gallons a minute. To break this down even further, you would have just 9 ½ ounces of tap water for each piece (and that includes both washing and rinsing).
Energy: the amount of energy used by an automatic dishwasher varies from 1.59 kWh and 0.87 kWh per load.
With hand dishwashing, the energy consumed is in heating the tap water. Assuming you are using the hot water faucet and not boiling the water, you would use around 0.28 kWh with a gas water heater, 0.43 kWh if it is a gas storage water heater. An electric storage model uses 0.28 kWh, while a tankless water heater would use 0.35 kWh.
Going by these figures alone, it would seem that hand dishwashing is the better option as far as being greener and saving money. So much for theory though; would it really be possible to wash and rinse 54 pieces in just the amount of water that comes out of the faucet in only two minutes? Four gallons of water for both washing and rinsing so many dishes doesn’t seem much to me – it actually works out at one cup of water for every plate!
In the real world, it looks as though the dishwasher wins in both categories – it is the greener option and also is more cost-effective.
There are some conditions to declaring the machine the winner though! Aren’t there always?
It is only the most efficient and cost- effective if you run it with a full load. However, you are able to increase its advantage by using the machine’s ‘light’ cycle and not using the drying period at the end of the cycle (this uses heat to dry the dishes).
Hopefully I haven’t confused you too much with all those numbers but it’s great to have reached an informed decision about which method of getting the dishes cleaned is the best way to go. Go green and save money at the same time, that’s the way I like it!
What have you experienced? Do you hand wash or dish wash and why?