Have you ever investigated Oxine AH (AH stands for animal health)?
It can kill many/most bacteria, viruses, etc. It is routinely used in livestock
water. Also used in intense bio-security situations.
It is also OMRI approved for organic use.
Might be a way to control your problem.
http://lilyproducts.com/OxineAHsalesbrochur.pdf
Hint: It is also used in the organic food industry, and for beer brewing...is the most common material used for flushing beer tap lines in pubs. You might find it cheaper in such places than vet suppliers, ie:
http://www.acechem.com/new/oxine.html