Tuesday, September 23, 2008

Water Down the Drain

By Chris Olson

A major aspect of my Lutheran Volunteer Corps year deals with forming intentional community around the three tenets of Social Justice, Sustainability, and Community. One of the issues that our house as been talking about is water conservation, specifically around our dishwasher. We didn't expect to have many amenities in our house since so much of the LVC experience is about simplified living, but were surprised to find a well furnished home when we arrived (thanks to the generous folks at Ballard First Lutheran next door and the keenly honed rummaging skills of past LVC house dwellers). Dishwasher use immediately became one of our topics of conversation. Some of us saw the community value in chatting around the sink while doing the dishes. I have had wonderfully rich conversations with past roommates while holding a sponge in one hand and a dirty plate in the other. My other housemates were pushing for filling the dishwasher and spending community time doing other things, getting the dishes out the way and moving on with the night. Ultimately the decision came down to the LVC tenet of sustainability, would we save more water using our dishwasher or washing our dishes by hand? We all thought we knew the answer, but each housemate had a different idea with a different logic behind it and all of them made sense in one way or another. I started to do some research on the subject and found a few articles and studies that compared dishwashers vs hand washing.
Here is a summary of what I found:

The first dishwasher was created in 1850 and consisted of a wooden box with a hand-cranked wheel that splashed water onto the dirty dishes (HA!). Since the mid 1800's, dishwasher technology has evolved and throughout the latter half of the 20th century grew in popularity. According to a study done by Virginia Polytechnic Institute and State University, the two main problems with dishwashers stem from energy and water efficiency. The authors of the study write, "The implementation of energy standards for appliances by the U.S. Department of Energy established new benchmarks for energy and water efficiency. A significant proportion of the energy savings for today's automatic dishwashers comes from the reduction in hot water use. Because energy is used to heat water, less water use by a dishwasher also means reduced energy use. In 1978, 83% of a dishwasher's energy use went to heating water, with 10% used for washing and 7% for drying (Enders, 1978). By 1994, only 56% of the energy used by the dishwasher was to heat water (Whirlpool Corporation, 1993). A significant reduction in water usage resulted from designing more efficient wash systems that incorporate direct water delivery and improved soil-handling systems (Dzierwa, 1994). The average water use per dishwasher cycle decreased from a range of 11-15 gallons per normal cycle in 1978 (Garrett, 1978) to 6-10 gallons per normal cycle in 2000 (Soap and Detergent Association [SDA], 2000)."

The dishwasher has become a more viable option in recent years, especially when compared with recent studies on hand washing dishes. "Scientists at the University of Bonn [pdf] in Germany who studied the issue found that the dishwasher uses only half the energy, one-sixth of the water, and less soap than hand-washing an identical set of dirty dishes. Even the most sparing and careful washers could not beat the modern dishwasher."

However, even when using a dishwasher some people still wash-by-hand to a certain extent. This has direct consequences on water conservation. "One consumer decision that greatly affects water and energy usage during dish washing is rinsing the dishes before washing them in the dishwasher. If dishes are pre-rinsed using a dishwasher pre-rinse cycle, approximately one gallon of water is used. Pre-rinsing in the sink under running water, however, uses up to 25 gallons of water for 5 minutes of pre-rinsing--a substantial difference. In the study discussed here, 93% did some pre-rinsing of dishes in the sink, and 48% rinsed five or more times per week. With the estimated water use of up to 25 gallons per meal, this practice represents a substantial use of water and energy."

So, dishwashers seem to be the better choice as long as you have a recent model and stay away from pre-washing your own dishes. My LVC house is still working out the details on our simplicity strategy, but its nice to have a little back ground to base our decision on. I'm placing two of the article links at the bottom of the blog and the other research paper has a link if you click within the text on the "University of Bonn".



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