When compared to other plumbing materials, the health, safety and economic benefits of copper are significant. Copper is impermeable and biostatic - contaminants don't penetrate it, and copper surfaces actually inhibit the growth of harmful bacteria. Copper tubing and fittings won't burn or melt in a fire. And, in the long run, the cost of copper plumbing systems is equal to or less than other materials when repairs over the life of the materials and higher home resale values are factored in.Copper is used for water pipes because it is very corrosion resistant in water and can last for decades. However, copper is not always used for the inner tank of the water heater. The best heaters have a copper container. But, most units today are made out of steel lined with glass or porcelain. To prevent the steel from rusting, a galvanic cell is set up with a sacrificial anode of magnesium or aluminum — when the anode is used up, the tank will rust.