CPV code 90913200 designates Reservoir cleaning services in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
90913200 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 90913000 (Tank and reservoir cleaning services).