What Is a Stainless Steel Submersible Sewage Pump? A submersible sewage pump is designed to operate underwater, usually installed at the bottom of a tank, pit, or well. Its primary function is to transport liquids containing solid particles, sludge, and wastewater from one place to another. The stainless steel version differs from standard cast iron or plastic pumps in one key aspect: its material. The main components, including the pump casing, impeller, and motor housing, are made of high-grade stainless steel such as SUS304, SUS316, or even duplex stainless steel. These materials make the pump ideal for corrosive environments, ensuring long-lasting protection against rust and chemical wear.