Factory pre-charge: 38 psi (pounds per square inch). Maximum working pressure: 100 psi. Maximum operating temperature 200 F (degree Fahrenheit). Meets NSF (National Sanitation Foundation) Standard 61 requirements for clean, safe drinking water. Inline pressure tank, heavy-duty steel shell with high-gloss enamel finish. Bacteria-resistant butyl rubber diaphragm with seamless construction for uniform strength, polypropylene liner and copper lined acceptance fitting provide a corrosion-resistant water reservoir and a reliable water-tight seal. Meets FDA (Food and Drug Administration) requirements for potable water supply.