The survival of Legionella in rainwater

Legionella is an environmental bacteria and a significant worldwide public health problem. These bacteria can survive a long period of time in distilled water, and more than a year in tap water. Due to these characteristics we were interested to explore how long it will survive in rainwater and if heavy bacterial contamination or bacterial microbiota would affect its survival. Rainwater is a good alternative source of water in households and is used for watering gardens, washing yards and as bathing water. The rainwater from ten different tanks was analyzed and the results showed that in 90 % of samples the number of microorganisms is elevated. Two rainwater samples were chosen according to the amount of microbiota and survival of L. pneumophila and L. longbeachae was monitored. The results showed that both types of Legionella have been able to survive for 30 days in the rainwater samples but haven’t been able to replicate. The rainwater microbiota restricted the survival of both Legionella strains although the effect was more pronounced in a case of L. longbeachae. These results indicate that both Legionella species can survive in the rainwater environment which means the rainwater could represent a reservoir for Legionella.