You Don’t Save Money Using A Dishwasher

Article Summary:



We calculate the ten-year cost of two dish washing methods as follows:

  • Manual Hand Washing: $754
    • $670 towards electricity, water, and detergent
    • $84 towards equipment costs (one new sponge each month)
  • Dishwasher: $897
    • $447 towards electricity, water, and detergent
    • $450 towards equipment costs ($350 for dishwasher unit purchase and $100 for installation)

Therefore, a dishwasher costs $143 more over a ten-year period.

  • Using an automatic dishwasher costs less to wash dishes on a per-wash basis because it uses less energy, water, and detergent
    • However, the upfront cost of buying a dishwasher adds $450 to the ten-year cost, which makes hand washing cheaper. (The average lifespan of an automatic dishwasher is 10 years)
      • If you are a renter and your landlord is responsible for buying and installing the dishwasher, then using an automatic dishwasher is less expensive because you don’t have to pay equipment costs for the automatic dishwasher
      • If you are a homeowner and you are responsible for replacing the dishwasher, then manual hand washing is less expensive because of the smaller equipment cost
  • You may still consider using an automatic dishwasher to save time
    • If you use an automatic dishwasher, increase the efficiency of this method by doing the following:
      • Always wash a full load of dishes (no partial loads)
      • Use lower temperature settings to conserve energy
      • Do not rinse dishes before putting them in the dishwasher. Instead, scrape dishes with a brush (and without water).
        • A dishwasher is capable of cleaning dishes without a rinse
  • The environmental impact of the two dish washing methods is unclear.  Although manual hand washing uses more resources on a per-wash basis, we could not find any data on the environmental impact of the manufacturing of automatic dishwashers.

Full Article:

On a per-wash basis, manual hand washing and an automatic dishwasher differ in the following ways:

Metric Automatic
Dishwasher
Manual
Hand
Washing
Energy Consumption (in kWh) 1.3 1.7
Amount of Water (in gallons) 3.5 13.0
Amount of Detergent (in ounces) 0.6 1.0
Cleaning Score 4.2 3.7
  • An automatic dishwasher uses less resource on a per-wash basis
  • An automatic dishwasher cleans dishes better too.

Using U.S. national average price for electricity, water, and detergent, we can calculate the cost per-wash of each method:

Cost Component Automatic
Dishwasher
Manual
Hand
Washing
Energy Consumption $0.16 $0.20
Amount of Water $0.01 $0.05
Amount of Detergent $0.05 $0.07
Total Cost Per Load $0.21 $0.32
  • An automatic dishwasher costs less to operate on a per-wash basis.
  • However, we also need calculate the equipment costs associated with each method
    • A dishwasher unit costs $350 with a $100 installation fee.
    • Manual hand washing requires sponges.
      • If you wash dishes frequently, then a sponge should be replaced once a month.
      • A new sponge costs about 70 cents.

Using the per-wash costs and equipment costs, we can calculate the ten-year cost of ownership.  (Note: The average lifespan of a dishwasher unit is 10 years.)

Metric Automatic
Dishwasher
Manual
Hand
Washing
10-Year Washing Cost @ 4 Loads Per Week $447 $670
10-Year Equipment Costs $450 $84
Total 10-Year Cost $897 $754
  • Therefore, an automatic dishwasher costs $143 more over a ten-year period
    • If you are a renter and your landlord is responsible for buying and installing he dishwasher, then using an automatic dishwasher is less expensive because you don’t have to pay equipment costs for the automatic dishwasher
    • If you are a homeowner and you are responsible for replacing the dishwasher, then manual hand washing is less expensive because of the smaller equipment cost
  • You may still consider using an automatic dishwasher to save time
    • If you use an automatic dishwasher, increase the efficiency of this method by doing the following:
      • Always wash a full load of dishes (no partial loads)
      • Use lower temperature settings to conserve energy
      • Do not rinse dishes before putting them in the dishwasher.  Instead, scrape dishes with a brush (and without water).
        • A dishwasher is capable of cleaning dishes without a rinse
  • The environmental impact of the two dish washing methods is unclear.  Although manual hand washing uses more resources on a per-wash basis, we could not find any data on the environmental impact of the manufacturing of automatic dishwashers.

 



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