Water-heater durability cannot be predicted reliably from tank material alone. Construction details, water chemistry, installation quality, temperature, usage, maintenance, corrosion protection and the manufacturer's design all matter.
Common storage heaters often use a steel tank with a protective lining and corrosion-control components. The condition and service requirements vary by model, so the owner's manual is more useful than a generic lifespan number.
Some heaters use stainless-steel components or tanks. Stainless steel can offer good corrosion resistance, but alloy grade, fabrication, water chemistry and warranty terms differ. It should not be assumed to be maintenance-free.
Copper is common in heat-transfer components and some tankless designs. Mineral scale can still form on hot surfaces and in narrow passages, so material choice does not eliminate water-quality considerations.
Non-metallic materials avoid some corrosion mechanisms, but heaters using them still contain valves, fittings, heating elements and other components with their own service limits.
Compare the exact model's warranty, approved water-quality range, maintenance requirements, local service availability and replacement-part support. If hardness or scale is a concern, use an actual water test and the manufacturer's guidance rather than choosing a heater from an unsupported "years of life" chart.