Selection of an effective biocide to control microbial damage to relics is important for cultural heritage conservation. Traditionally, selection methods depend on growing bacteria under controlled conditions in lab. However, some microorganisms cannot be studied well because they do not grow well under these conditions. Furthermore, the methods cannot be applied for rapid onsite detection and identification of certain microorganisms. Recently, some rapid detection methods for viable microbes have been developed that do not require cultivation and can solve these problems. This study reviews traditional and current rapid detection methods. It is found that an adenosine triphosphate (ATP) bioluminescence technique, works very well, both in the lab and onsite for the evaluation of the effects of multiple biocides on relics. The method provides a new way to select biocides for cultural heritage conservation.