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Apr 2, 2008 07:31 AM


I read somwhere or heard somewhere or dreamed that coffee grounds and eggshells are the only organic substances that will not bio-degrade. I am therefore reluctant to put these down my disposal, for fear of messing up my system ( I'm on septic, as I live in back of beyone) Any truth to the coffee grounds/eggshell quandry? Harold McGee? Anyone??


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  1. I see both coffee grounds and egg shells recommended for composting so I think you can safely assume that they are quite bio-degradeable.

    1. A mixture of coffee grounds and eggshells is a great fertilizer for roses, so if you don't want to put in your disposal use them on your roses. And they do bio-degrade.

      1. I know you're not supposed to put them down a garbage disposal to get ground up...apparently eggshells can mess with the blades somehow? They were on the no-no list an old landlord gave me along with stuff like potato skins and plastic forks (duh...). It doesn't seem like they'd cause much of a problem, though.

        That mixture of grounds and shells is also good to keep cats away from your vegetable garden.

        1 Reply
        1. re: bbbron

          Actually the egg shells are recommended to help clean the blades, and ice is good too. Here is a bit more info: