Monitoring San Francisco Public Utilities Commission's Chloramine Conversion with GIS

In February 2004, the San Francisco Public Utilities Commission (SFPUC) switched from chlorine to chloramine disinfection for drinking water. GIS maps helped communicate the status of this drinking water additive as it progressed through San Francisco for 30 days.

Chloramine is regarded as a better disinfectant than chlorine alone because it lasts longer in water to more effectively remove pathogens such as bacteria and viruses. Compared to chlorine, chloramine produces lower levels of trihalomethanes, suspected carcinogens that form when chlorine mixes with natural organic substances in water. Customers from other water utilities report improved taste and odor in their water when chloramine disinfection is used.

During the systemwide conversion, sampling results were displayed using GIS software, which provided the various SFPUC departments (Project Management, Regulatory, Treatment, Distribution, Customer Services, and Communications) with the following benefits: a visual display of the progression of chloramine throughout the city and county of San Francisco, communication of water regulation compliance, guidance to operations staff for enacting various response activities, helping Customer Services respond to customer inquiries, and troubleshooting operational problems and consumer complaints.