Widespread education is critical in reducing injuries related to showerhead temperatures and the presence of Legionella bacteria in water heaters.

Figure 1


In 1973, the American Society of Sanitary Engineering introduced its ASSE Standard No. 1016 - Individual Shower Valves: Anti-Scald Type - to provide product performance criteria for those devices designed to prevent scalding. 

Shower valves meeting the requirements of this standard limited the potentially hazardous sudden surges of high-temperature water to flow from the showerhead, thus limiting the exposure to scalding hot water. Since that time, this standard has seen many revisions to the performance requirements and also to the type of devices covered by the standard. The latest version, ASSE  No. 1016-2005, is titled Performance Requirements for Automatic Compensating Valves for Individual Showers and Tub/Shower Combinations.

Between 1973 and the present, many new products and five new ASSE standards have been developed to control the water temperature of various types of devices at many differing applications. Now, with many devices meeting and some exceeding the requirements of the standards, we still experience scald injuries and slip/fall injuries in showers from sudden surges of excessively hot or cold water. 

According to The National Safe Kids Campaign: “Hot tap water accounts for nearly one-fourth of all scald burns among children and is associated with more deaths and hospitalizations than other hot liquid burns. Tap-water burns most often occur in the bathroom and tend to be more severe and cover a larger portion of the body than other scald burns. In 2002, an estimated 92,500 children ages 14 and under were treated in hospital emergency rooms for burn-related injuries. Of these injuries, 22,600 were scald burns.”

Figure 1 shows the ideal shower temperature for an average adult male to be 110º F. The times reduce dramatically for infants, children younger than 14 years of age, the elderly and the handicapped.

The American Journal of Public Health, the Consumer Product Safety Commission and all the model plumbing codes prefer and specify 120º F as the maximum allowable water temperature for delivered hot water. We simply cannot rely on the codes to provide all the necessary requirements for the safe delivery of domestic hot water. At 120º F, we must be aware scalding remains a very real issue.

Another very real danger related to bathing is thermal shock, which is the physical reaction to a sudden change in water temperature caused by a pressure or temperature disturbance in the hot-water delivery system. This temperature change can be from either colder or hotter water. This sudden change in water temperature can cause a serious slip/fall injury. In many of these cases, the bather will grab for anything to help break the fall and will accidentally grab the shower valve, thus further increasing the water temperature and potential for more serious injury.

In terms of scalding, first-degree burns are the least critical, penetrating into the epidermis layer of skin resulting in redness and minor pain at the burn site. Second-degree burns include blistering and damage to the epidermis layer and can penetrate into the dermis layer. Some superficial blistering and increased pain at the site may occur. 

Third-degree burns penetrate the full thickness, cause irreversible damage to the epidermis and dermis layers and underlying tissue, according to ASPE.

So what problems are we dealing with here?  

  • Many of the homes (approximately 80 percent) built prior to 1973 still have non-compensating valves in use.

  • Many of the compensating valves installed were never adjusted properly to set the limit stops.

  • Many devices have been installed in an incorrect application.

  • Many new water-efficient (low-flow) devices are being installed without regard for the resultant flow restriction.

  • Inattention, if only for a moment, when bathing of children, the elderly and the handicapped can result in scalding.



  • Figure 2

    Education and Awareness

    During the past year, ASSE President Ron Murray and I had the privilege of being introduced to representatives of the Home Safety Council and Safe Kids, both advocacy groups promoting safety in the home. Of course, we got into conversations concerning the topic of potential scalding situations and what their safety message is to prevent scalding.

    In May, I met with Meri K. Appy, president of the HSC, and Dr. Angela Mickalide, director of education and outreach, to discuss how our two organizations could work together on scald prevention and scald awareness issues. And as many things go, this was sort of put on the back burner. But then, as I was about to leave my term as international president and turn the reins over to Ron, I met with him to see what ASSE could do to move forward on this much-needed program.

    Ron, in his opening address to the 2010 ASSE Board of Directors, announced the formation of the Committee for Scald Awareness and asked me to chair the group. The purpose of this committee is to work with our industry partners and the various advocacy groups to promote public awareness of the potential hazards and injuries caused by scalding water. 

    In December, a press release was issued calling for volunteers. The response was outstanding. The 22 current members on the committee represent all facets of the industry. 



    What's the Plan?

    The first order of business is to write and publish a position paper on the effects of low-flow showerheads on compensating and non-compensating shower and tub/shower combination valves. In many areas of the country, water purveyors and other agencies are distributing low-flow showerheads free of charge to promote water efficiency and conservation.

    We embrace water conservation initiatives and applaud these agencies for striving to save our most critical natural resource. There is quite a bit of information being circulated concerning increased risk when these low-flow showerheads are installed on both compensating and non-compensating valves. Many factors come into play with the performance of these showerheads. This committee will sort through all of this information and arrive at a position the ASSE Board of Directors will publish.

    Another primary goal of this committee is to dispel some of the myths and misconceptions (many of our own doing) concerning the proper temperature to set a domestic water heater. We will use a many-pronged approach to get the message across. One approach, with a technical flavor, will be geared toward the plumbing industry, including plumbers, engineers, contractors, designers and trade groups.

    For the second part, we plan on teaming with our advocacy partners to help get this message to the general public but in more layperson terms that the moms and pops can understand.

    A good part of this message will deal with the inherent problems of water heaters – the stacking effect of the water within the heater. Our water heaters are one of the most reliable appliances in our homes. They get installed and essentially forgotten about for the next 10 or more years. As stated earlier, most are set at 120º F at the factory, which brings some problems into the picture. Scalding still happens at this temperature. Also, there may not be adequate hot water, which brings into play the ideal temperature for the growth of Legionella bacteria.

    First, let’s look at the stacking effect in uncirculated water heaters. Figure 2 (upper left) shows the water heater thermostat set at 120º F, which allows a temperature swing of (plus or minus) 15 to 18 degrees. The colder water, being denser, stays at the bottom of the heater. The layers of heated water, many times compared to a stack of pancakes, rise to the top of the heater with the hottest being at the very top and the first water drawn. As shown, this water can easily be 150º to 160º F, dangerous temperatures that can cause instantaneous and serious burns.

    The other problem with the thermostat at 120º F is Legionella bacteria thrive within a narrow temperature range of 68º to 122º F. Legionella is a type of pneumonia and, unless specifically targeted or tested for, many cases are misdiagnosed as pneumonia.  

    The Centers For Disease Control has estimated Legionella infects 10,000 to 15,000 persons annually in the United States. OSHA estimates more than 25,000 cases of the illness occur each year, causing more than 4,000 deaths (CDC estimates 30 percent who contract will die), according to a report by the Association of Water Technologies.

    It seems as if we are in that proverbial catch-22 dilemma here. If we recommend lowering the hot-water delivery temperature, we reduce the risks of scalding injuries, but we then increase the risks of Legionella bacteria growth. But if we recommend increasing the temperature, the risks change places. When you bring energy conservation into the equation, the solutions become a little more challenging.

    Nevertheless, with the diverse qualifications of the members of the ASSE Committee for Scald Awareness, I believe we are up to the challenges.