When evaluating disinfection ...
Published by Nathan Hardy
When evaluating disinfection in water systems it's very important to measure reduction in biofilm, opposed to just reduction in planktonic counts. To measure biofilm reduction I suggest a BioGEORGE or DATS for a large system. A CDC Biofilm Reactor is great for small scale testing.
In a water system I would suggest coupling biofilm monitoring with ATP testing (quick/easy) of the bulk water. This will give great indication of disinfection.