Dishwasher or dishes: which uses more energy and water?


What you think intuitively is often wrong. A dishwasher should be more environmentally friendly than washing dishes by hand. You read it over and over again.

This statement goes back to research Consumer research on dishwashing habits in four European countries from the University of Bonn in 2010. Unfortunately, this calculation is not correct.

Many factors should be taken into account in order to make a truly accurate estimate of electricity and water consumption. In this article, we’ll at least show you how you can make better decisions about your kitchen.

Problem with the research

Unfortunately, this was not a minor flaw in the study. Otherwise, the calculation could have been added up in the meantime, because since then dishwashers have become more economical in terms of water and electricity consumption.

Production and transportation must be included in energy consumption (Photo: Han Chenxu/Unsplash)

However, two factors that had a significant impact on the calculation were then ignored:

  1. The study only looked at redness itself. The energy required to manufacture and transport the dishwasher was not included.
  2. Hand-washing subjects at the time used a wide variety of techniques, from economical to extremely wasteful. The study used an average. However, economical hand washing was more economical than dishwasher.

Comparison of water consumption

At first glance, the water consumption of washing dishes by hand and by machine seems to be the same. The sink holds about nine liters of water. A dishwasher also needs about nine liters per wash cycle.

However, with this amount of water, the machine cleans many more dishes. Also, when I used to wash by hand, I used even more water per wash cycle. Both effects change the calculation in favor of the electronic device.

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A plate with leftovers
Coarse residue should always be removed from the plate before washing it in the dishwasher (Image Pixabay/congerdesign)

When the dishes were dirty, I changed the rinse water because it was just too dirty. For rinsing, I either ran a second basin with clean water, or kept each glass, each plate under running water for at least a short time.

On the other hand, the machine is also able to reuse dirty water and use it several times – apart from the final rinse, which of course uses fresh water again.

But the lesson from the above study is that water consumption is not the same for everyone. It depends a lot on the individual technology – then water consumption can really be lower than dishwashers:

  • remove all food residues after meals
  • If possible, do not let anything dry out
  • if you do, let it soak well with a little water
  • add some water to the bowl
  • trust the soapy water even if the water is a little cloudy
  • rinse only a few items, such as glasses

Comparison of energy consumption

Energy consumption is even more difficult to determine. Eco program dishwasher consumes from 0.7 to 0.95 kWh. Unfortunately, this is not so easy to assess when washing by hand.

Where and with what is the water heated? In an electric kettle under the sink? In a gas heating system? Central heating? Does it run on gas, oil or central heating? What’s the queue in your kitchen? Is the hot water already at the tap? how much water you use

Heating system
How is water heated for washing hands? (Photo: avanttrend / Pixabay)

Instead of trying to calculate a specific value here, focus on how you can save energy by hand washing.

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The dishwasher has a 60 degree eco program, but when washing by hand the water is never, ever hotter than 60 degrees. Your hands can’t handle it. It is written everywhere that microbes die only at a temperature of 60 degrees. However, washing up liquid does most of the cleaning work. The rinsing water should not be warm.

On the other hand, the high temperature in the dishwasher is important to maintain the machine and remove the biofilm that may have formed on the appliance. Temperature is also used to remove scale from pots and pans.

Dishwashing liquid comparison

When washing dishes by hand, it is easy to overdose on detergent. Bottles often have an opening that is too large. But in the end, it comes down to how to properly dose the detergent. Trust the instructions on the bottle first, then increasingly your…

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