Factory pre-charge: 38 psi (pounds per square inch). Maximum working pressure 100 psi. Maximum operating temperature 200 F (degree Fahrenheit). Engineered to provide years of trouble-free service using cold rolled steel for a higher strength to weight ratio. Rugged, stable steel base with protective plastic strip. Heavy-duty butyl rubber diaphragm and durable polyolefin liner to prevent corrosion. Waterworker tanks feature an appliance quality finish which is resistant to sunlight and harsh conditions. All tanks are completely lead free for safety. Meets NSF (National Sanitation Foundation) Standard 61 for clean, safe drinking water. 5 year warranty. Blue tank.