it entirely depends on where you live. In places where the is a water shortage, then paper is the better option. If water is more prevalent, then washing is the way to go.
Typically the plates will be worse because with the food on them they cannot be recycled. But water conservation can be really important in some areas - so check that out. Also you may want to check out how "green" your city is, in the terms of how well they recycle and the situation of it's landfills. (you should be able to contact your city/town government for this information)
When you wash, try to use "green" soap and use luke warm to cold water. If you're washing them immediately it's not really necessary to use hot. If you wait to do all the dishes for the day until night - then I would use hotter water to ensure sanitation. (also if you have anything really dirty, like something that had raw chicken on it - go ahead and use the really hot water). Whenever you can, don't have the water running. You can do this by filling up the sink part way with soapy water, washing the dishes and storing them in a drying rack, and then when you're all done, gently rinsing all the dished at one time, instead of rinsing each dish separately.
Also, I'm not sure of your monetary situation, but if you can afford it get an energy saver dishwasher. Those can be run every two days, which saves on water, heat and your hands :-)
· 1 decade ago