A very interesting study! It reminds me of a very pertinent issue which is the use of the Ganges in India for religious traditions, often leading to increase in water-borne diseases. Here is a paper I found after a quick PubMed search
http://www.ncbi.nlm.nih.gov/pubmed/16546805
Would you phrase questions more specifically at certain religions/denominations? And if so how would you do it sensitively? A very hard task i feel!
Thank you for the post