DBPs that are formed from water disinfectant chemicals reacting with naturally present organic matter at water treatment centers are transported through the water distribution system to the public. These DBPs end up in the water we use for everyday living. These agents can be transported into our bodies through the ingestion of drinking water, and inhalation and dermal contact from showers, swimming and dishwashing, among others.
Another issue that has gone largely unnoticed is the subject of DBP development in wastewater that is often released to surface water systems. Wastewater is often heavily chlorinated in an effort to kill excessive levels of fecal coliform bacteria associated with human waste. As a result, NOM and THMs can also be an issue for surface and groundwater systems, particularly those that are recharged directly or indirectly via treated wastewater. Excessive concentrations at the outfall may be diluted down and there is evidence to suggest that THMs will volatilize, but many chlorinated and brominated compounds are stable in the environment. The long-term implications of THMs in freshwater supplies are still being studied and may be a concern for the future. Remember, we all live downstream.