Guidance for Monitoring Building Water

Centers for Disease Control and Prevention. Guidelines for environmental infection control in health-care facilities: Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee. MMWR. 2003;52(RR-10):1–42.

D. Recommendations—Water
D.II. Routine Prevention of Waterborne Microbial Contamination Within the Distribution System

1. Maintain hot water temperature at the return at the highest temperature allowable by state regulations or codes, preferably ≥124°F (≥51°C), and maintain cold water temperature at <68°F (<20°C). Category IC (States; ASHRAE: 12:2000)
2. If the hot water temperature can be maintained at ≥124°F (≥51°C), explore engineering options (e.g., install preset thermostatic valves in point-of-use fixtures) to help minimize the risk of scalding. Category II
3. When state regulations or codes do not allow hot water temperatures above the range of 105°F–120°F (40.6°C–49°C) for hospitals or 95°F–110°F (35°C–43.3°C) for nursing care facilities or when buildings cannot be retrofitted for thermostatic mixing valves, follow either of these alternative preventive measures to minimize the growth of Legionella in water systems. Category II
   1. Periodically increase the hot water temperature to ≥150°F (≥66°C) at the point of use. Category II
   2. Alternatively, chlorinate the water and then flush it through the system. Category II
4. Maintain constant recirculation in hot-water distribution systems serving patient-care areas. Category IC (AIA: 7.31.E.3)