I had responded earlier to someone's question about using CS for pet urine 
outdoors. I forgot one item. If you use EIS you may want to mix some essential 
oil with CS before adding the soap. There is a patent that claims that adding 
pepermint oil to CS prolongs its effectivity in the stomach. I think it may 
also apply to your intended usage. You might also try essential oils other than 
peppermint as well. 
 - Steve N