14. Tank failures (leaks) caused by operating the water heater in a compulsive DEFINITIONS OF POTABLE WATER or contaminated atmosphere. Contaminant Laval 15. Damages, malfunctions, or allures caused by operating the water heater | Total Hardness 200 mg/l with an empty or partially empty tank (“dry firing”), or failures caused by (Residential Use Below 140°F {12 gravitational) operating the water heater when it is nat supplied with potable water, free to | Water temperature) circulate at all times.