Your water heater may be the origin of two common health dangers: the chance of scalding and the chance of infection from bacteria that thrive in hot water inside the heater. These can be inconsistent hazards since eliminating one possibly makes the other more likely unless additional safeguards are taken. The temperature on gas-fired and electric water heaters is set by a thermostat dial on the heater tank. Most thermostat dials incorporate a detent at the 120 degrees Fahrenheit mark. As the dial is rotated, it is going to cease at that stage and need marginally extra power to move it below or above that temperature. Many homeowners choose to keep the temperature below 120 degrees to cut back scalding risk or to save energy. But raising the temperature above 120 degrees is recommended by many health specialists to reduce the danger of exposure to germs, as long as cautionary measures to avoid scalding are executed, also.
The most poisonous bacteria found in water heaters is Legionella pneumophila, known to be the origin of Legionnaires’ disease, a potentially fatal lung infection often misdiagnosed as common pneumonia. Trace levels of the bacteria are usually present in municipal water supplies but don’t thrive in the cold temperatures. Once inside a hot water heater, however, Legionella bacteria multiplies and is conveyed through the household pipes, where it might be inhaled from the aerosol mist that accompanies showering, bathing or even washing dishes at a sink. Very young children and older men and women are particularly at risk.
The Temperature Factor
Water heater tank temperatures in the area of 120 degrees create a supportive environment for the presence of Legionella and other bacteria. The temperature setting on a water heater thermostat actually only represents a maximum temperature when the tank is full and totally heated. Temperatures from the tank often fall below the suggested maximum as hot water is cold and used water circulates into the heater. It is at these lower temperature ranges of 95 degrees to 115 degrees Fahrenheit that Legionella bacteria multiply and become established inside a water heater. A study from the American Society of Sanitary Engineering demonstrated that the bacteria cease to multiply when water temperature reaches 120 degrees. They are not destroyed at that temperature, however, and can survive to be conveyed to an outlet such as a shower head or tap.
Scalding injuries from hot water are a danger to all ages. But they are most likely to influence children and the elderly who often cannot react quickly enough to remove themselves from too hot water. Sensitivity to exposure to hot water increases exponentially since water temperature rises. At 120 levels, skin demands an average of three minutes exposure to sustain a first-degree burn. At 131 levels, burns may occur in as little as five minutes.
Raising the Temperature
The American Society of Sanitary Engineering recommends putting the temperature of water heaters to 135 degrees to 140 degrees Fahrenheit, a range shown to destroy bacteria such as Legionella. At these temperatures, bacteria may neither thrive or live to contaminate fixtures lodged in the heater. Adjusting a water heater to a greater temperature should always be accompanied by the installation of anti-scald apparatus in the home by a certified plumber to prevent potential burn injuries, even if such safeguards are not already present.
Anti-scald devices are available in three types: A temperature-actuated mixing valve is put near the water heater’s hot water heater and automatically mixes cold water into the hot water to reduce the temperature to 120 degrees. An automatic compensating mixing valve is located at the point of use — generally a shower or tub — to mix cold water and bring the water temperature to a safe level just before it emerges from the shower head or tub spout. A temperature-limiting device is generally used at sinks and lavatories and maintains temperatures to a predetermined setting indicated on a manual dial up.