Many drinking water plants use water from rivers, reservoirs, or lakes as their raw water sources.  These surface waters invariably contain some levels of pathogens that must be inactivated prior to distribution, as well as organic material (such as decaying plant matter). To insure that water is safe to drinking, the USEPA mandates that a sufficient quantity of disinfectant is added to generate a residual concentration at the customer’s taps.

Disinfectants can react with the organic material in drinking water to form disinfectant by-products (DBPs), and epidemiological studies have identified that certain classes of DBPs are human carcinogens. The USEPA mandates that drinking water plants processing surface water achieve specific levels of total organic removal in order to reduce the public’s exposure to these carcinogens.

All inorganic coagulants are capable of achieving some level of TOC removal.  Alum, ferric sulfate, and ferric chloride tend to be better than ACH/PACl based products for removing colloidal organic carbon (i.e. “dissolved organic carbon”).  The coagulant type and dosage required for treating any specific raw water must be determined by onsite product evaluation.