Table 1.

The four steps of the Water Safety Plan (WSP) for the control of Legionella implemented at the Hospital ‘Santa Marta e Santa Venera’.

System assessment	Description of the system
	Description of the system focused on water piping, hot water production, at risk devices, water uses.
	Identification of risks Risk areas were not ranked into different levels. Risk level was considered high in all the wards as all patients were considered potentially at high risk.
	Identification of the operational monitoring barriers
	Disinfection of the WDS with MC. Ensuring that the system operates safely and correctly and is well maintained. Yearly visual inspection of the accessible parts (storage tanks, distal outlets) of the WDS for damage and signs of possible contamination. If debris or scales or biofilm are found, then the inspection must be carried out more frequently. Scale control by maintaining the cleanliness of the water softener. Routine cleaning procedures for distribution system (storage tanks, distal outlets). Semesterly draining of the hot water storage tanks. Weekly flushing for several minutes of taps and showers when they are not in regular use. Use of sterilized water to clean respiratory equipment. Cleaning and disinfection protocols for respiratory equipment.
	Identification of the control measures Checking the performance of the disinfection system (MC at 2 mg/L residual level): daily monitoring of oxidation-reduction potential on-line monitoring of hot water with an ORP probe mounted on the device; monthly determination of MC, free and total chlorine; semesterly determination of free ammonia, nitrite and nitrate. Temperature control for hot and cold-water systems. Monthly heterotrophic colony counts at the storage tanks and distal outlets as an indication of whether microbiological control is being achieved. Four-monthly sampling and testing for the presence of Legionella in the WDS and at the point of use to show that adequate control is being achieved.
	Assessment of the water distribution system CPPs and permanent monitoring.
Monitoring	Identification of control measures	Flushing of the outlets, preliminary piping sanitization, continuous disinfection with MC.
	Monitoring control measures	Legionella surveillance, determination of ammonium, nitrites and nitrates levels, check of temperature, water quality (including ORP on line monitoring), residual disinfectant concentration, flushing protocol, maintenance procedures.
Management and communication	Development of supporting programs	Medical and nursing staff, technical and housekeeping staff were trained to actively participate to the WSP implementation tasks.
	Preparation of management procedures	Different levels of risk were considered, depending on various water system parameters. Situation under control (Legionella < 1.000 ufc/L; cold and hot water temperature at the outlets <22 °C and 48–50 °C, respectively; MC at 2 mg/L residual level; free ammonia < 0.50 ppm; nitrites < 0.50 ppm; nitrates < 50 ppm). Alertness (Legionella between 1.000–10.000 ufc/L; cold and hot water temperature at the outlets >22 °C and <48–50 °C, respectively; MC at <2 mg/L residual level; free ammonia > 0.50 ppm; nitrites > 0.50 ppm; nitrates > 50 ppm). Alert threshold (Legionella > 10.000 ufc/L). Management procedures were prepared by the risk manager and the facility manager with the support of the Legionella experts. Situation under control: no action required. Alertness: correction of water temperature; correction of MC dosing. Alert threshold: hyperchlorination (20–50 mg/L for 1–2 h, respectively); raising of the MC concentration (5 mg/L for 1 h); flushing of each outlet for 5 min.
	Documentation and communication procedures	Medical directors and the risk manager supported by the Legionella experts established procedures that should be followed by any person involved in the WSP implementation. Documentation management followed ISO9001:2008 principles.
Surveillance	Validation of the WSP	Legionella sampling and analysis were accepted as validation for the effectiveness of the implemented WSP.
	Sampling program	Sampling program included a sampling campaign after preliminary sanitization and continuous monochloramination.
	Auditing	Several audits were carried to validate the WSP measures. After the start of continuous disinfection with monochloramine new audits were carried out to assess the actual implementation of the WSP measures and define the improvement plan.
	System assessment	Reviewed every year and after any major changes to the WDS or management (e.g., changes of water quality; engineering changes).