Principles of dishwashing and dishwasher design

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To choose a method of washing dishes with minimum cost, environmental impact and effort requires an understanding of the underlying processes.

General principles of cleaning:

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More of any of these will help to clean more effectively:

  • Water (or other cleaning fluid). The environmental impact depends on quantity and also how it is reused or disposed of.
  • Detergent. Using less water achieves a greater concentration of detergent and thus less impact. The choice of detergent is also important.
  • Heat. This can greatly increase cleaning effectiveness, but causes carbon emissions, unless using solar hot water, or water heated with renewable energy.
  • Time. This is usually a matter of managing the process so that there is maximum time for dirt, grease etc to dissolve, and has no environmental cost.
  • Physical motion (scrubbing or agitation).

Using more of one component can help reduce the amount used of the others. Allowing time to soak and dissolve is one of the most important tools in effective and low-impact cleaning, as it reduces the impact of the other components.

Hand washing dishes[edit | edit source]

Soaking in hot water with lots of detergent will greatly reduce the amount of work needed, but can increase the environmental impact. Choose solar hot water and an environmentally friendly detergent.[1]

Rinsing[edit | edit source]

For large amounts of washing: Two stages of rinse water can be used, or one stage and immediately dried with a towel.

For small amounts: Rather than leaving the water running, stack the washed dishes. Then run the rinse water over the stack - as the top items and rinsed and placed on the draining board, the water used to rinse them helps to rinse the dishes underneath.

Drying[edit | edit source]

Paper towels use resources (trees and energy) unnecessarily.

Draining minimizes the exposure to pathogens that may grow in tea towels (although these are not generally passed from towel to dish). More importantly, it saves work of drying, and of cleaning the cloths.

Drying racks exist which double as storage areas, so that dishes, crockery and cutlery are washed, placed to drain, and are ready to use for next time. This is the most convenient option. This means that the dishes are stored in the open, rather than enclosed in a cupboard; however, they are face downward, not close to floor level, and may have a horizontal cover over the top, thus minimizing any settling of dust onto the surfaces used for eating. (What about cutlery?)

Dishwasher design[edit | edit source]

Eco cycles in current washing machines can give disappointing results, leaving dishes greasy. How can the results be improved while reducing the use of energy, water and detergent. A "super-eco" cycle, lasting much longer than a standard cycle, could take advantage of the power of soaking by:

  • Very briefly spraying with water at intervals of several minutes (close enough together that they never really dry out) - just enough to wet the dishes, and begin the process of loosening and dissolving the fats and other residues. This should continue long enough to make the actual washing very easy, but not so long that it uses substantial water. An "overnight option" could be used to allow a long period, if this gives the best results.
  • Rinse water could be stored to be used for the pre-rinse in the following wash. Is there a health concern with the impurities, left in the rinse water, becoming septic when left for a period of time? (For health reasons this may not be a good design approach.)
  1. Is there actually a significant difference between detergents?