Phosphorous is the primary corrosion inhibitor used in industrial cooling towers and it is a basic nutrient for biological growth. When phosphorous enters open waterways it can cause algae and microbiological blooms that can consume oxygen and cause fish kills and Governments around the globe are restricting the discharge of nutrients such as phosphorous. The tighter discharge restrictions of phosphorus in industrial water treatment make the requirement for low environmental impact corrosion inhibitors more urgent. Compared with other corrosion inhibitors on the market this new low phosphorous corrosion and scale inhibitor for cooling water has shown good corrosion and scale control in bench top laboratory pilot cooling tower and field trials. This paper will review the laboratory and field work involved in developing this product.