The septic tanks (plastic tanks) of ASIO, spol. s r.o. are made by welding structural elements and boards made of integral polypropylene or polyethylene and their copolymers, both homogeneous as well as lightweight. At the customer’s request, the plastic tanks may be equipped with technological partitions or various technological openings for the connection of pipelines. Septic tanks are normally designed as closed tanks with a non-supporting plastic lid or with a cast-iron cover suitable for walking on. The plastic tanks may be produced as food-grade tanks enabling contact with food. The septic tanks are waterproof, as defined by ÈSN 75 0905. The structural design and static verification of plastic tanks are based on the modern calculation method of end elements.