(B) Inspect Facility and Collect Water Samples: Inspection: The building should be inspected to identify all potential Legionnaires' disease bacteria (LDB) sources including: (a) Water-cooled, heat-transfer systems; (b) Domestic water systems; (c) Humidifiers and misters; (d) Any sources of water that are maintained above 68°F (20°C) and have a potential for being aerosolized. Water Sampling: Collect appropriate water samples to determine LDB levels before shutting down the water systems. These sample results will be invaluable in establishing the cause of the outbreak. Before flushing or disinfecting the water in suspected sources, take water samples for analysis to determine the predominant serogroups and subtypes of L. pneumophila in the water source and to determine the number of colony forming units (CFU) per unit of water. (a) This information may be helpful in identifying the source of the disease if the subtype of L. pneumophila has been identified in the afflicted workers. (b) Because sampling for LDB can be inconclusive, sampling results alone should not determine the appropriate course of action in a building where an outbreak has occurred. Corrective actions should begin immediately. (c) Water sampling protocols specific to each operating system are described in Section II. See more from topic source: https://www.osha.gov/html/a-z-index.html