In a foundry owning 5 cooling towers, analyses performed on 19 March 2002 on request of the local Prefecture revealed the presence of legionella on 2 of the 5 towers (respectively 200,000 and 1000 CFU/liter). Any result above 1000 CFU/liter require a specific chemical treatment to eliminate these bacteria and then conduct follow-up analyses to check efficiency. Exceeding 100,000 CFU/liter immediate shutdown, complete drainage of the circuit, and subsequent installation disinfection have to be triggered. Another set of analyses was then scheduled. Those 2 stages were repeated as long as the legionella concentration remained greater than 1000 CFU/liter. The Classified Facilities Inspectorate addressed an official letter to the operator recalling actions to be carried out and the appropriate departments to be contacted should a legionella outbreak occur. The operator drew up a report on actions undertaken: shutdown, drainage and disinfection of the most heavily contaminated tower; disinfection for the other tower; and a new set of analyses on all 5 towers. These follow-up analyses indicated contamination of 3 of the 5 towers (50,000 CFU/liter instead of 200,000, 6000 vs. 1000, and 1100 CFU/liter for a 3^rd tower). Revised treatments were implemented bringing the most contaminated tower down to 1375 CFU/liter, but for the 2^nd tower the concentration actually rose to 50,050 CFU/liter. After another treatment, the analyses performed on 14 November showed rates of 450 and <50 CFU/liter, respectively. On 8 January 2003, the health and human services informed the inspection authorities for classified facilities that a foundry employee had been hospitalised after contracting Legionnaire's disease. The plant operator was immediately contacted to take the necessary actions to prevent contamination of others employees. Analyses once again revealed a high concentration in one of the towers and its cooling tank (625,000 and 13,000 CFU/liter, respectively). The standard treatment to cope with results above 100,000 CFU/liter was applied. The employee had likely contracted the disease during high-pressure cleaning of the cooling tank without wearing breathing protection. His exposure was not life-threatening. The Inspectorate requested analyses be conducted every 15 days. If the operator fails to solve this recurrent problem, the Inspectorate will propose a shutdown of the cooling towers.