The specifications and exclusive design features of the system protect against any occurrence of static water, growth of algae, contamination from corrosion or bacteria, or accumulation of externally introduced material.The most prevalent rainwater catchment tanks around the world are composed of virgin polyethylene. Other available materials are plastic (polyethylene), concrete, galvanized steel, as well as fiberglass and stainless steel which are rust and chemical-resistant. Each of these materials has its own pros and cons