ISO 11731-2:20 04描述了一种用于分离和计数拟用于人类使用的水（例如热水和冷水、用于洗涤的水）、用于人类消费的水和用于处理过的洗澡水（例如游泳池）中的军团菌生物体的监测方法。它特别适用于潜在军团菌数量较少的水域。由于军团菌的生长可能被膜上其他细菌菌落的过度生长所抑制，因此该方法仅适用于含有低细菌的水。

ISO 11731-2:2004 describes a monitoring method for the isolation and enumeration of Legionella organisms in water intended for human use (e.g. hot and cold water, water used for washing), for human consumption and for treated bathing waters (e.g. swimming pools). It is especially suitable for waters with prospected low numbers of Legionella. As the growth of Legionella may be inhibited by overgrowth of other bacterial colonies on the membrane the method is only suitable for waters containing low bacterial.