Drinking water quality concerns from chloramine-induced degradation of elastomeric compounds

Over the last decade, chloramines have often been used in place of chlorine as a disinfectant because of US Environmental Protection Agency (USEPA) regulations associated with disinfection by-products (DBPs). Although the switch has generally been beneficial, several utilities have reported problems with substantially higher rates of elastomeric component degradation in the distribution system. To investigate the influence of elastomer degradation on water quality, accelerated degradation tests were performed for three of the most commonly used elastomers: natural rubber, styrene butadiene (SBR), and sulfur-cured ethylene propylene diene monomer (EPDM-S). Test solutions were then analyzed for suspended solids and organic compounds. Most of the organic compounds identified were associated with leaching of compounds from the elastomers; the exception was chloroform, which is thought to be a reaction by-product. The presence of these organic compounds is considered to be persistent because they are continually added to the system as elastomeric compounds degrade over time.