1.1 ,This practice outlines a procedure for evaluating the efficacy of microbicides (algicides, bactericides, and fungicides) that will be used for controlling microbial growth in cooling water systems. The microbicides will be evaluated using simulated or real cooling tower water against (1) microbes from cooling water, (2) microbes in microbiological deposits (biofilms) from operating cooling systems, or (3) microorganisms known to contaminate cooling water systems, or a combination thereof. This practice should be performed by individuals familiar with microbiological techniques.