Dangers Associated With a Forgotten Appliance: Water Heaters - PART I

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By Thomas J. Wuori, JD


In every living situation, from residential houses, apartment complexes, nursing homes, to hotels, there sits a water heater. By design, water heaters are basically large storage tanks that hold water. At the bottom of gas-fired water heaters are pilot lights and main burners. The pilot lights are on 24 hours a day, 7 days a week. The pilot lights are located close to the floor and hidden behind a cover plate. When the heater senses a need for hot water, the pilot light will ignite the main burners, heating the water to the set temperature of the thermostat. If there are no mechanical or service problems, the water heaters can sit unnoticed and forgotten for well over a decade.

However, during those years, water heaters can be, and historically have been, involved in dangerous and devastating accidents leading to serious burn injuries and death. In litigation, they have been referred to as (A) the flammable vapor ignition hazard and (B) the scald hazard. In part through litigation, changes and advances are being made. More needs to be, and can be, done. Part one of this two-part article will address the flammable vapor ignition hazard.


Every household at one time or another contains flammable liquids – from gasoline, to paint thinner, to camping fuel, to mineral spirits. What many people do not realize, much less appreciate, is that it is the vapors from the liquid, when mixed with the right combination of air, that ignite and burn. These vapors are (1) heavier-than-air and will stay low to the ground, (2) are invisible, (3) can migrate significant distances (10, 20, 30 or more feet), and (4) ignite and flashback from a wide variety of ignition sources (pilot lights, open flames, sparks, etc.). Because many water heaters are floor-mounted, with their constantly burning pilot lights behind the cover plate, the pilot light serves as a ready ignition source for the low-tothe-ground vapors.


Below are real-life examples from cases involving the flammable vapor ignition hazard:

  1. A 2 year-old boy goes into the basement of his parents apartment, which had a play area separated from the utility room. Within a short span of time, the boy is able to climb over a barrier into the utility room and find a gas can. Liquid spills from the can and the vapors combine with air. Whoosh. A water heater pilot light ignites the vapors. The boy in this particular case is burned over 98% of his body.
  2. A college-bound senior working a late shift comes home and goes into the bathroom inside a basement utility room. He accidentally knocks over a can of camping fuel left there, and there is a flash fire before he can even stand up and begin to clean up the spill. Within 6-7 feet is a floormounted, residential gas-fired water heater. He is severely burned.
  3. A young man, at his parents’ home, working on his race car in the family garage, unexpectedly has racing fuel leak out from the fuel line. While trying to stop the flow, his mother gets him some water for his eyes and then goes to open the door. Suddenly, there is flash fire. He is severely burned over 80% of his body. Within 10-15 feet from the spill is a residential, floor-mounted, gas-fired water heater with a constantly-on pilot light.
  4. A man agrees to remodel a friend’s basement. While he is cleaning up paint spills using paint thinner mixed with water, there is a flash fire that starts from underneath the door to the utility room, which houses a floor-mounted, residential, gas-fired water heater 30-40 feet away. 

Top image: Quick start of ignition of vapors with unelevated water heater inside closet. Bottom images: Gasoline spill with elevated water heater – no ignition after 28 minutes and 22 secondsThese types of fires and burn injuries have been occurring annually for well over 30 years. For example, in 1975, the Consumer Product Safety Commission (CPSC) contracted with the Calspan Corporation for a study that concluded in part even then that:

  • In terms of frequency and severity of injury, the accidental ignition of vapors from flammable liquids was the number one hazard associated with the mere presence of the appliances considered in this study…
  • Adult victims generally realized that the liquid they were working with was flammable, but were totally unappreciative of the distance the vapors could travel and ignite. Child victims were usually imitating adult behavior, e.g., “refueling” a piece of “equipment” … often a toy …
  • Accident locations coincided, of course, with the general location of the appliances, i.e., the basement, the kitchen, and the garage…
  • The presence of an appliance utilizing room air for combustion insures that there will tend to be a natural flow of air toward the flame. The higher the burner rating, and the physically lower the location of the burner, the more hazard would be anticipated with respect to fume ignition. This is consistent with the pattern observed, and explains the frequent involvement of water heaters in flammable liquid accidents…

Realistically, educational programs can be expected to provide only limited success. What is desired is more positive control. . . (“Investigation of Safety Standards for Flame-Fired Furnaces, Hot Water Heaters, Clothes Dryers and Ranges,” July, 1975).

However, essentially from 1975 to present date the response has still been made that the flammable vapor ignition hazard is only one of “consumer misbehavior.” Even moreso the industry continues to claim that this consumer misbehavior is “unforeseeable.” This despite the statistical evidence that annually approximately 20 deaths, 360 injuries, and millions of dollars in property damage occur when flammable vapors are ignited by gas-fired water heaters.

Lawsuits have been brought against the hot water heater manufacturers, plumbers, and gas companies. One of the common claims we have made in these lawsuits is that the residential, gas-fired water heaters should be sold with stands and installed on an 18 inch stand (or higher) where possible. Why? Because the higher the pilot light (ignition source) the less likely the heavier-than-air flammable vapors are to be ignited. Water heaters are required by law to be installed 18 inches or higher when located in a garage. Basements and utility rooms are other such areas where these accidents occur as noted by the Calspan report in 1975. Testing has shown that elevation works:

NFPA 54, 5.1.9 reads: Installation in Residential Garages: 

  1. Gas utilization equipment in residential garages shall be installed so that all burners and burner ignition devices are located not less than 18 inches above the floor.
  2. Such equipment shall be located, or protected, so it is not subject to physical damage by a moving vehicle. 

Experts we have retained (and who did this testing) have recently published a peer-reviewed article to be published in Fire Technology in the year 2003, which supports the elevation concept.

Unfortunately, many residential, gas-fired water heaters are installed on the floor in basements, utility rooms, and even garages. Thus, the fires and injuries have and will continue to occur. While stands to elevate the water heaters exist, the stands are not sold with the product and elevation for the most part simply does not happen except in certain circumstances.

Because of the continuation of these severe accidents, lawsuits brought as a result of them, and media reports by shows such as PrimeTime Live, the CPSC has finally pushed the industry to address the problem from a design standpoint. One manufacturer, American Water Heater Company, has designed and offered for sale in late 1999 a product that addresses the issue by design –its Flame Guard™ Safety System. And many other manufacturers are part of a Joint Water Heater Consortium specifically created to address this hazard from a design standpoint.

However, until all of the residential gas-fired water heaters are replaced, a process that may take an additional 10-20 years, you should check for and address (1) your water heater location, installation and elevation options, and (2) what flammables are or may be used, stored, or brought in areas where there are pilot lights or other ignition sources, including but not limited to the pilot light of the water heater. Elevation may be necessary or required. Control of flammables is always necessary and advisable. Normal household activities such as cleaning a paintbrush or using a cleaning agent, or an unexpected spill, can lead to catastrophic and deadly accidents.


  • Do not store or use flammable liquids in your house. Flammable liquids include but are not limited to gasoline, paint thinners, propane cylinders, lighter fluid, cleaning products, mineral spirits, rubbing alcohol, nail polish remover, furniture polish, floor polish, turpentine, camping fuel, disinfectants, adhesives, and glue.
  • Look at your water heater, furnaces, dryers, and other appliances and read all warnings and labels attached to them.
  • Look at the area in which these appliances, including the water heater, are located. Are flammables located in the area? Are flammables likely to be brought, stored or used there any time in the future? You should consider whether your water heater can be safely elevated and keep all flammables out of the house. If you are going to be in the market for a replacement water heater, consider the designs that address the flammable vapor ignition hazard.
  • If your water heater is located in a garage and is not elevated, it is likely a code violation and you should consult with your local building inspector and a professional plumber.
  • Store your flammables in appropriate containers, properly sealed and located away from ignition sources.
  • Consider safety cans for flammables such as gasoline. Safety cans have spring-loaded selfclosing tops and many of them have "flame arrestors" inside of them to minimize the risk or extent of fire. They are not much more expensive than plastic cans, especially given the useful life of these cans and their safety features. See e.g. http://www.labsafety.com (and search for safety cans).








This story is an excerpt from The Phoenix Society’s® Burn Support News, Spring Edition 2003. Burn Support News is a quarterly publication that contains articles on the emotional, psychological, and social aspects of burn recovery.  All Rights Reserved.
The Phoenix Society, Inc.® • 1835 R W Berends Dr. SW • Grand Rapids, MI 49519-4955 • 800.888.BURN • http://www.phoenix-society.org