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Episode 1: The Results

Hand washing is the winner...but only by a nose.

The most efficient machine dishwasher is, for all practical purposes, just as efficient as the most efficient method of hand washing that we tested. In fact, in order for the hand washing to win, you need to use about 4 gallons of hot water or less on average, which means that if you find yourself frequently replacing the wash water because it gets too dirty (even once!), then our most efficient dishwasher would probably do a better job.

We tested three ways of hand washing dishes: leaving the water running constantly; filling a sink to wash and turning on the water to rinse; and using one sink for washing and another for rinsing. We stacked them up against a 10 year old dishwasher, a brand new dishwasher with the lowest efficiency that we could find, and a brand new dishwasher with the highest efficiency that we could find.

Here’s how they shaped up, assuming that you only fill the hand washing sinks up once:

If you have to replace the wash water once during hand washing, here’s how the results change:

Don’t have a top-of-the-line dishwasher, or the money to replace yours right now? That’s okay.

The good news is that even the least efficient new dishwasher that we could find was still pretty efficient.

The clearest result, however, was that letting hot water run while you’re doing dishes (or pretty much any other time) is a really bad idea. Even turning it on and off every single time you rinse a dish still saved a lot of energy. So if you can’t do the most efficient thing, at least get in the habit of turning of hot water when you’re not using it. And if you can’t seem to break the habit, you’re better off (by a potentially long way) using your dishwasher.

And if you are in the market for a new dishwasher, remember that Energy Trust of Oregon incentives on appliances will be expiring at the end of 2011, so now is a great time to consider that upgrade.