In 2016, officials at DWS were informed that their sole supplier of chlorine gas planned to cease providing the product in June of 2017, giving them roughly one year to get new disinfection systems up-and-running at six surface water treatment plants and three well sites.

As DWS officials evaluated alternatives to gas chlorine, they sought autonomy from chemical supply companies serving the Hawaiian Islands. Additionally, they wanted a technology that would increase safety and resiliency in case of a natural disaster. Officials performed an evaluation of alternative forms of chlorine bleach by comparing both the capital equipment and operating costs, as well as the costs and risks of handling hazardous materials. DWS compared bulk sodium hypochlorite, calcium hypochlorite, and on-site sodium hypochlorite generation (OSHG). Recent changes in local safety standards required DWS to reduce or eliminate hazardous materials used in proximity to local schools. The sodium hypochlorite produced on-site, at 0.8% concentration, met the requirements since it is below the hazardous material threshold of 1%. The OSHG option satisfied DWS’s need for safety, autonomy and resiliency, while still achieving the lowest overall life cycle cost.