disinfectant to water leaving the aquatic and soil filters of the greenhouse. The pump then sends this chlorinated water back to the toilets for reuse and to the landscaping in front of the building for irrigation.
The Department of Insurance requires that all plumbing associated with indoor reuse be specially and prominently labeled to prevent cross connections between potable and non-potable water.
Despite its routine and required use, chlorine is extremely potent and potentially hazardous to environmental and human health. Although chlorine is a disinfectant, when chlorine combines with organic matter it produces carcinogenic compounds called trihalomethanes. Also, the production and use of chlorine can lead to the formation of other toxins, such as furans, chloroform, and dioxin. Recent studies have shown a direct link between dioxin exposure and human cancer (Source: International Agency for Cancer Research, February, 1997). Recent research by the National Research Council shows dioxin to be 300,000 times more carcinogenic than DDT. Regulatory decisions related to the use of chlorine are based on balancing its benefits as a disinfectant with its potential adverse impacts.
Disinfection and related regulatory responses are areas in need of research and reform. Increased reclamation and reuse of water should help prompt these changes. For example, regulations which are based on coliform counts as indicators have been used for years in the assessment of pathogenic bacteria and viruses. It is widely known that coliform counts are poor indicators of pathogen concentrations. New assays are under development, but are not widely available.
Coliform assay is one of the current critical regulatory requirements for water reuse. The increased reuse of water and its related need for effective disinfection will hopefully move the chlorine and coliform debates forward.