Wednesday, November 07, 2007

Bless That Dishwasher

I've become obsessed with the whole Dishwasher vs. Hand Washing issue. Due to the drought we’re having in North Georgia, this question is rather pressing for us right now. Regardless of the drought though, the complete environmental impact of the dishwasher is causing me stress now that I’ve been forced to look at it to begin with. I’m like a dog with a bone sometimes…

After I mentioned my new hand washing pact in my last blog entry, I got a couple of comments on whether hand washing is, in fact, a more efficient use of water. And while I got my hopes up for a couple of minutes there (because truly, my dream was that someone would show me the numbers proving that the dishwasher is better), after plodding through numerous discussions of this question online, I found that not only does no one seem to agree on the answer, but that the only studies "proving" dishwashers are more water-efficient appear to have been sponsored by the manufacturers.

So, here’s the thing. I’m not a scientist. And I can never be totally sure that anything I've read online is completely true. But I do love a challenge.

What I found so far is that the average dishwasher uses between 9 and 15 gallons of water in a cycle. Half of the things I’ve read online claim that even the most conservative hand washer will use more than that washing a load of dishes. For the most part, I initially begged to differ. When I hand wash the dishes, I turn on the faucet to rinse the dishes in the beginning, then I turn off the water entirely while I scrub everything with soap on a sponge, and I turn the faucet back on to rinse everything at the same time. Total time to do this whole process on a typical day, when I’m washing three sets of dishes along with the pots and pans and everything else used to cook an entrée and one or two side dishes takes less than 10 minutes. And obviously I’m not running the water during that entire time.

When I was still using the dishwasher (sigh), I ran it an average of once every two days, working out to about 7.5 gallons of water usage per day. So clearly, the question is whether I’m using less than 7.5 gallons of water when I hand wash the dishes each evening now, and I thought the answer was patently unclear. But how on earth was I supposed to figure this out for sure? And why was it that I couldn't find an answer to this conundrum online? Could it really be possible that I’m the first fool to try and compute this number? Say it ain’t so…

Well obviously I’m not the FIRST person to think of this. A little bit more googling yielded the following answer: a typical kitchen faucet uses 4 to 7 gallons of water per minute. Hmmm. Now the variance seems large with that answer, but even if my faucet uses the low end of that number (4 gallons of water per minute) and even if I’m only running the water for 4 minutes, then I’ve already used more than the dishwasher would have used on a full load. And I would have only been hand-washing HALF of what would fit in my dishwasher (on the basis that it took me two days to fill a dishwasher load).

Here’s the rub though: if you use the sink to pre-rinse each dish before putting it in the dishwasher, then you would still have to add that kitchen faucet usage to the dishwasher usage in order to see your total usage, and that final number would probably get ugly. However, I’ve read in countless places that pre-rinsing dishes before putting them in the dishwasher is a complete waste of time and water, and that there is no compelling reason to do so.

Of course, there’s still the caveat of not trusting everything you read online, but suffice to say, I’m shocked that the dishwasher APPEARS to be the winner here. And I’m relieved. SO VERY RELIEVED. Actually, I’m so doggone happy that I would do a jig if only I knew how. I’m definitely making dessert tonight.

Note: I’m not taking energy usage into account for now. It is obvious that dishwashers use more electricity than hand washing, and I’m nowhere near smart enough to figure out what happens when one weighs the water savings against the added energy usage to get the best environmental answer. Truly though, in a time of water crisis, I would rather err on the side of using more energy in order to use less water. So for now...


FatcatPaulanne said...

I'm so glad you did this research. I love my dishwasher deeply. Now if I could only get one of those Roomba vacuums!

Hopefully, they are energy efficient!

Linda up north said...

We are not short of water but rather it is the electric bill that is bothering me :) hmmmm.... Well for now I still have dishwasher soap, so the machine wins (hooray)... at least for today.

Anonymous said...

Check the water meter before doing the dishes. Wash the dishes, and make sure no one else in the household is running any water. Check the meter after doing the dishes. Do this a few times, to make sure that you have a good average.

Do the same thing with running the dishwasher. (Maybe go out while the machine is running, so nothing can come up where you must turn on a faucet, etc.)

Now you can compare actual water usage in your house.

(Sorry, I don't have a google account yet. I'll set up one soon, so I won't be anonymous.)

Sarah Beam said...

Alas, anonymous, we don't have a water meter. Out here in the country, we are on a well and do not draw from city water.