Corrosion Inhibitor for Open Cooling System is an all organic chlorine stable, non volatile liquid corrosion inhibitor and scale dispersant, which has been designed for use in conjunction with biocide treatments, used for control of bacteria. The Corrosion Inhibitor is an alkaline blend of organic, anodic and cathodic corrosion inhibitor, a threshold deposit controller and sludge conditioner offering protection to multi metal system without the requirement of additional specific corrosion inhibitor. The Corrosion Inhibitor contains no controversial constituents such as heavy metals or phosphates whose use is becoming increasingly restricted. The Corrosion Inhibitor for Open Cooling System offers protection over an extended range of pH, temperature and raw water hardness, making an ideal treatment for both building services and industrial application.