Legionnaires Disease and Water Supplies...
 

Expressed in another thread, Legionnaires Disease is found in ponds, lakes, rivers, groundwater, and even soil. (!) In water brought into every house this bacteria can multiply to dangerous levels. It's worse in water softening devices, but any dead-ends in plumbing (like water-hammer devices) can be affected. Anywhere indoor water is allowed to stagnate in the pipes increases the hazard, which is increasing in the US.

The disease is contracted by inhalation of fine bacteria-laden water droplets, usually grown in house water heating systems. Recommendations are to keep ones hand's off the water heater's thermostat.

Where one operates water heater "management" from the breaker panel, heated water should be "used-up" and cold water allowed to flow at all other times.

I don't think anyone has suggested that the temperature be turned down.

I believe that most come set at 140F.
The federal government suggests no less than 120F.

LD prefers less than 113F.

''The most important factor for the possible development of Legionella bacteria in tap water systems is the design and operation of the system. It is well known that Legionella thrives in water that is insufficiently flushed and is allowed to remain stagnant for too long between the critical temperatures (20ºC to 45ºC). Regular and thorough flushing at or above 60ºC permanently reduces the Legionella growth.''

I would guess that second homes will show the condition more often that active first homes were the water doesn't have the same stagnation period.