CETCO Passive Water Polisher (CPWP) is designed to work unattended and can be made suitable for unmanned locations. An Oil & Grease Analyzer can be installed on the existing facilities discharge outlet to actuate a 3-way valve that diverts produced water to CPWP for polishing to achieve NPDES Overboard water discharge criteria for federal leases in the Gulf of Mexico. CPWP has a compact footprint of ~100 sq/ft.