The world's leading manufacturer of polyethylene tanks, Norwesco has been producing polyethylene septic tanks since 1980. With that kind of experience, Norwesco offers you proven products that you can count on for years of dependable, trouble-free service. Norwesco septic tanks are backed by a full three-year warranty from date of manufacture and have been approved by state and local health departments from coast to coast. Where applicable, Norwesco septic tanks have been certified by both IAPMO™ and CSA™.