Cob Use of cob to construct a greywater system

[Darlene_Conway at trca.on.ca]

I am designing a greywater system for a friend along the lines of Michael
Reynolds' Earthship system. I was ready to consider the use of cement with
pop cans until I found out about cob last summer. I would much prefer to
avoid the high embodied energy of aluminum cans and cement and go with cob
instead. With a water-tight lining, I am wondering if cob would do the
trick just as well. Any comments or suggestions out there? Thanks.