This International Standard specifies culture methods for the isolation of Legionella and estimation of their numbers in water samples. This method is applicable to all kinds of water samples including potable, industrial, waste and natural waters. This method is also applicable for water related matrices e.g. biofilms, sediments, etc.. There are at least 58 different Legionella species described. Not all Legionella species are culturable; therefore, the methods described in this International Standard may not recover all species of Legionella.