Residential Water Heater Damage and Fires following the Loma Prieta and Big Bear Lake Earthquakes

Abstract

To obtain data on the extent of earthquake damage to residential water heaters, and the effectiveness of prevailing water heater restraint methods, we surveyed 299 randomly-selected people who lived in the City of Santa Cruz, California, at the time of the 1989 Loma Prieta Earthquake. We also reviewed the rate of water-heater linked fires in the Big Bear Lake area following the 1992 Big Bear Earthquake. In Santa Cruz, 13% of the respondents' water heaters suffered damage from the earthquake, most commonly water leaks costing under $50 to repair. Two percent of the water heaters suffered gas leaks. No water heater related fires were reported in our sample or in the City of Santa Cruz following the earthquake. Repair costs for solar water heater systems averaged over $600 per damaged system. The sample revealed no quantifiable reduction in earthquake damage associated with reported prior water heater strapping with plumbers tape. In the Big Bear Lake area, 11 out of 13 structural fires were attributed to water heater gas leaks. Water heater-related fires occurred at a rate of roughly 6 per 1,000 structures. Further studies are needed to compare the effectiveness of different water heater restraint methods, and to identify factors that contribute to ignition in water heater related fires.