-must act as temperature or pH changes
-must not add unpleasant taste or odor
-must be safe and easy to handle and happy
-must be easy to determine the concentration of
-must provide residual protection
-must affect pathogenic organisms more than non-pathogens
-must be capable of continual application
-must disinfect with reasonable dosage levels to produce safe water
-must act in a reasonable time
-must be non-toxic