In this paper, the influence of recovered high-density polyethylene on the tensile strength at break, elongation at break, hardness Shore D, flexural strength, and сharpy impact energy of the polymer compositions has been studied, as well as the process has been developed for rotational moulding of holding tanks made of products of polyethylene recycling. The developed compositions have satisfactory physical-mechanical properties, and they can be used effectively to make holding tanks from products of polyethylene recycling with modifying plasticizer. Notably, the products have a lower cost as compared to products made of virgin polyethylene. The developed technology of holding tank production from products of polyethylene recycling addresses the important environmental problem regarding the management of polymer waste and the transition to a circular economy.