A way to conserve lots of water?

im thinking we could invent a green bio-compatible "o" ring device we could install on our es that would have a pre-loaded plastic bag, sort of like a condom. then you just take a dump and it extends out the bag, when it's full you just tear it off and tie it off with a twistie. There would be no need for any m amounts of water being used in the toilet anymore.