Copper-, stone- and glass-lined water heaters perform better than unlined aluminum or galvanized steel heaters.
A stainless steel alloy called HWT is designed to resist corrosion as well as the lined models.
Unlined galvanized steel tanks perform least well, but they are the least expensive and may prove satisfactory in localities where the water supply does not have adverse effects on equipment.
To stop tank corrosion, a magnesium-coated metal rod is available. It is hung inside the tank 3″ or 4″ away from the bottom. Because the magnesium paper eventually will be eaten away, the rod should be inspected from time to time and replaced when necessary.
Better-grade, non-metallic gas water heaters are also popular.
The tanks, although more expensive than metal models, are light, easy to install and corrosion-proof.
Advise homeowners to partially drain their water heater once or twice a year to remove the accumulation of sediment, which can affect operation.