Plant for the continuous treatment of water metoric and car wash composed of a primary grit removal monoblock unit in PE rotomoulded linear high density equipped with IN / OUT PVC connections and NBR gaskets of variable diameter, oil removal monoblock unit in PE linear high density rotomoulded equipped with coalescence separator and non-emulsified oils and hydrocarbons and in / out PVC connections with NBR gaskets of varying diameter, a water well floodway linear rotomoulded monoblock high density polyethylene equipped with No. 3 PVC connections, NBR gasket of variable diameter, respectively for the input, output, and the connection to the by-pass, a biofiltration unit in linear PE rotomoulded equipped with membrane diffusers and a filter bed of plastic material, clarification water well and fiscal water well monobloc rotational molded high density linear PE with IN / OUT pVC connetions and NBR gaskets of varying diameter, a sand/antracit and acivated carbon automatic filters. All units are equipped with appropriate threaded inspection manhole.