Water and electricity consumption of dishwashers

Economical water consumption is not obvious advantage, it seems that the wash a few dishes by hands is more quickly and economical. To dispel this myth, consider an experiment conducted with an amount of dishes in one day. After identifying the water usage per year the rough estimates of water and electricity consumption will be reduced.

In the experiment, dishes are washed in the dishwasher and by hands. For hands washing was selected  the amount of dishes that is used for one day – at breakfast and dinner. This amount is less than the total capacity of a dishwasher.

water-usage-of-dishwashers

Economical hostess recommend to use the dishwasher once a day or even less – as filling the device completely. Dirty utensil accumulated it the dishwasher, and when it fully loaded it is activated by one button. Dirty dishes in the sink irritate the majority of housewives, so they have to wash it more often than once a day.

Water usage: the experiment

1 method – using a dishwasher

Samsung dishwasher with 2 large compartments and 1 shelf height 5 cm for cutlery:

  • Wash Mode – lightly soiled utensils (copes with any dirty dishes)
  • Duration – 29 minutes
  • Water temperature – 45 degrees
  • Capacity – roughly double amount of dishes that is washed by hands
  • Electricity consumption – 0.8 kWh.

Meter reading

Before After Water usage
Hot water (41,859) Hot water (41,859) Hot water (0  liters)
Cold water (79,317) Cold water (79,331) Cold water (14 liters)

Total water consumption – 14 liters.

2 method – washing by hands

washing-by-hands

  • Wash mode – the most economical, while soaping the water was shut off
  • The duration of the washing – 21 minutes
  • Water temperature – warm comfortable, close to the hot
  • The amount – about 2/3 of the capacity of the dishwasher, dirty dishes after dinner and breakfast.
  • The list of dishes (34 units) – 9 plates, 7 cups, 1 pan, 2 salad bowls, 1 cutting board, 1 teapot, 13 cutlery.

Meter reading

Before After Water usage
Hot water (41,937) Hot water (41,960) Hot water (23 liters)
Cold water (79,600) Cold water (79,620) Cold water (20 liters)

Total water consumption – 43 liters.

Thus, we see that the dishwasher is three times more economical. Also the device does not use hot water, which is much more expensive than cold.

Can assume: when washing dishes once a day for a year, we get the following figures:

  1. Dishwasher: 14 liters x 360 days = 5040 liters of cold water;
  2. Hand Washing: 43 liters x 360 days = 15 480 liters, including 7,200 liters of cold water and 8280 liters of hot water.

In large families, especially where children or adolescents wash dishes for an hour and not accustomed to conserve water, water usage can be ten times greater than shown in this experiment. In the experiment, hand washing takes only 21 minutes a day, which is a rarity.

If housewife washes dishes by hand several times a day and doesn’t turn off the water during the washing process, the water consumption per day may be at least 100 liters.

How much electricity does a dishwasher use?

Dishwasher consumes 0.8 kW per hour, respectively, one use needed = 0.8 kW x 0.5 hour = 0.4 kWh.

0.4 kW x 360 days = 144 kWh

The average cost of one kilowatt is 15 cents, so:

144 x 15 = 2160 cents or $21.6 – this is an additional price you need to pay.

When hand washing electricity is spent only for lighting (if you don’t use boiler). Of course, you have to pay over for electricity, but the savings on water cover electricity costs.

Time spent

Dishwasher works about 29 minutes per day or 10,440 minutes in a year (174 hours). When hand washing for 21 minutes per day hostess holds 7560 minutes or 126 hours per year. If washing takes an hour, the hostess holds 360 hours of her life. And it is 15 days a year, thrown into nowhere. In this regard dishwasher wins.

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