Concrete and steel are the most often utilized materials for storage tank construction. However, polyethylene, thermoplastic, and glass-reinforced plastic (fiberglass) are becoming more prevalent. The primary reason for this shift is cost. Storage tanks made from these materials are less expensive to produce than concrete or metal tanks. The choice of material for a particular application depends on many factors. These include physical properties such as density, weight, corrosion resistance, and elasticity; economic considerations including price per unit volume or weight; environmental impacts associated with production and disposal of waste products; and technical issues related to workability, repairability, and durability during use. Storage tanks must be able to withstand severe conditions created by their use. They must also provide adequate containment for hazardous substances. Finally, they must provide effective leak detection and repair procedures to prevent release of contamination into the environment. Materials commonly used in storage tank construction include: iron, steel, and stainless steel; fiberglass; polyethylene; and thermoplastic materials like polypropylene and high-density polyethylene (HDPE). Glass-reinforced plastics (GRPs) are also being used increasingly for storage tanks because they provide good structural strength while using less material than other types of tanks.