EOC 77 - When to Call the Plumber: Addressing a Deficiency in Hot Water Temperature to Mitigate Risk for Legionella in Ambulatory Care

Background: Legionella bacteria can grow and live in healthcare facility water systems and can cause Legionnaire’s disease when the bacteria are introduced into the lungs of susceptible patients. Legionella grows best in water at temperatures between 77F – 113F. One way to control Legionella bacteria in water systems is by controlling water temperature. In the obstetrics and gynecology (OBGYN) clinic the potable hot water temperature measured in the growth range. This led to an investigation to determine the root cause.

Methods: Water temperature was measured with a digital probe thermometer after one minute of flushing the fixture. Hot water temperatures below 110F (limit set by state plumbing code) were considered in the Legionella growth range. Time to reach 110F was also considered to determine severity of stagnancy. Review of fixtures and water heaters occurred, and flushing was performed to address potential stagnancy. A professional plumber was hired when interventions were unsuccessful.

Results: Annual testing at the OBGYN clinic showed that hot water was taking up to 5 minutes to reach 110F. Blocked aerators on fixtures were observed and removed. Water heaters were at appropriate temperatures. Flushing the water system increased temperatures within one minute, but this only worked with significant flushing and had to occur weekly. Review of the plumbing plans and field investigation found a hot water return valve was shut off. The return valve was turned on and subsequent testing confirmed the problem was resolved.

Conclusions: Routine water testing identified an issue with the potable hot water temperature, and corrective action occurred to reduce the risk for Legionella growth. Consulting a professional plumber assisted in identifying the root cause when other interventions were unsuccessful. Hot water failing to turn hot or taking a long time to turn hot could be an indication to staff that there may be a problem warranting investigation.