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Q. I’d like to see fairer comparison of handwashing dishes vs. using a dishwasher. I calculated how much water I use washing dishes by hand efficiently (with a tub, not running water) and my highest use (by day) was the same as an efficient dishwasher. Most days, I use less. Also, I don’t run on electricity.

Saying that dishwashers always save water is misleading and only true in the circumstances most favorable for dishwashers and least favorable for hand-washers. Please revisit. I can’t be the only reader who knows they use far less water washing dishes by hand.  

Beth R.
Sharon, Mass.

A. Dearest Beth,

Indeed, you are not the only astute reader who wrote in after my recent column on disposable vs. reusable dinnerware. And you’re right: Though the average washer of dishes will use far more water when scrubbing up by hand than when loading the dishwasher, I should have known my readers are far from average.

Let’s back up and take a look at the numbers: According to a widely cited European study, hand-cleaning 12 place settings guzzles, on average, 27 gallons of water. Compare that to a load in a new, Energy Star-certified dishwasher: All machines must use less than 5.8 gallons per cycle, and the best of the bunch sips just 1.95 gallons. The difference sounds stark, but that’s not the whole story.

In that study mentioned above, many of the test subjects – brace yourselves – ran the hot water continuously as they washed up. Some left the tap on even as they dried the dishes (!). Based on anecdotal observation from myself and others, this isn’t far from what plenty of Americans do, too. (My word, do they think clean water grows on trees?)  It stands to reason that washing dishes with conservation in mind will use much less water. But with the kitchen sink spewing 3 to 5 gallons per minute, can the conscientious cleaner really beat the dishwasher standard of 2 gallons or less? I believe she can.

There are several methods you can use to do so. Take the “two sinks” strategy and the “tub within the sink” approach, both of which employ one basin of hot, soapy water and one cold-water rinsing bath. Another variation substitutes the rinse tub for an ultrathin stream of running tap water, shut off after the suds wash away. Then there’s this method modeled by permaculture guru Paul Wheaton, in which he stops up the sink and reuses rinse water as scrub water.

To increase your chances of success, scrape every bit of food you can into the compost before washing and do dishes quickly, before food has a chance to congeal. You can even install a faucet aerator to choke off the flow to a mere 1 gallon per minute. And if you reuse the greywater to fill your toilet tank or water plants, you might not even have to count it against your dishwashing total.

So, let me state it loudly, and for the record: An energy-efficient dishwasher will not always beat a careful hand-washer in water savings.

I haven’t run this experiment myself, Beth, but I trust in your results. So much so that I have a New Year’s challenge for all hand-washing devotees out there: Put on your lab coat and find the absolute, rock-bottom amount of water necessary to get your dinnerware clean. Try the methods mentioned above, or create your own. Competition is a motivator, so it may help to jockey with your friends for position in the name of saving water. Strava for dishwashing, anyone?

Dehydratedly,
Umbra