Passionate Homemaking

In our recent discussion about the energy efficiency of the dishwasher, this question arose:

Tammy asked: I don’t have a dish washer, but I have also heard from someone (can’t remember who!) that dish washers use less water than hand washing. I wonder… how much water does a dish washer use for a load of dishes?? I don’t use much water at all for washing my dishes (maybe 3-4 gallons a day, total!)… but I have seen people wash their dishes by hand and run LOTS of water… so I would love to have hard numbers here!!

Here is the research and statistics I came across and things to consider…

1. Time

I think the major thing to consider is the amount of time it takes to wash dishes by hand. According to a statistic, dishwashers can save 230 hours of time! Since using baking soda, I use barely any water, and just load them right up! Takes maybe 10 minutes including the hand washing of the non-dishwasher items.

2. Water/Electricity

Several reports stated that the average handwasher uses 20 gallons of water per time at the sink, whereas a dishwasher uses 8-11 gallons. If you run your dishwasher once a day, you use 8-12 gallons, whereas if you handwash after each meal, you could be using 60 gallons. Hand-washing dishes typically uses significantly more water than running a dishwasher because most people tend to leave the faucet running or wash dishes several times a day. However, hand-washing by filling a dishpan or sink basin and not running additional water is shown to consume half of what a dishwasher uses per load.

It seems. Tammy, you fall into the second category. Good for you in using so little water! That would be a challenge for most people, including me. I would assume you wash your dishes only once a day? As that would be the most efficient way with this method, but then you have dishes piling high throughout the day (not my personal preference, if possible). Or not discard and replenish the water for each meal? 3-4 gallons would fill up my sink only maybe twice and then not be enough for rinsing, and boy that water gets dirty very quickly. Maybe you have some tips to share for the other hand-washers?

3. Sanitation

Automatic dishwashers clean and sanitize dishes far more efficiently than washing by hand. Statistics report that average bacteria count for machine-washed dishes is less than 1 per plate versus bacteria on dishes washed by hand which average a whopping 390 count per plate! Wow!

Conclusion

I think the bottom line is do your best with what you got!

- To get the most energy efficiency by hand-washing, you must fill up a sink of soapy water for cleaning rather than letting the tap run. Best to wash all in one batch per day. Use lots of soap! Hot water to rinse to best kill germs.

- To get the most enegry efficiency from a dishwasher, you must only run full loads! Don’t use the dry cycle, instead use air dry cycle, or open to dry, and use the baking soda tip to avoid pre-rinsing! Choose dishwasher that is energy star certified.

Here are a few websites that I found helpful in gathering this information:

Dishwashing vs. Handwashing

Bonn Study on the topic