Abstract: A system and a process for separating impurities such as grease, fuels and solid particulate matter, from water contaminated therewith, comprising passing the water to be treated through a first cleanable strainer bag assembly for filtering solids, a holding/settling tank for separation of an oily and water phase and for precipitation of solids, a second cleanable strainer bag assembly having at least one strainer bag of a porosity finer than the porosity of the strainer bag of said first cleanable strainer bag assembly, a heavy oil gravity separator, a light oil coalescer, a further oil and petrochemical and very fine solid separator with a replaceable polypropylene element for adsorbing or absorbing oil and filtering solids, and preferably also a carbon filter assembly. The invention makes possible the economical removal of impurities and the reclaiming of water with a residual impurities level of less than 5 parts per million.