Case Study

Town Of Hillsborough Relies On Hach For Free-Ammonia Testing And Nitrification Control

When Bay-area water wholesaler San Francisco Regional Water System (SFRWS) changed its residual drinking water disinfection process from chlorine to chloramine, the town of Hillsborough's Water Quality staff faced the challenge of updating its water testing procedures to prevent nitrification and continue to meet state-mandated drinking water quality standards. While chloramine reduces overall levels of certain regulated disinfectant byproducts, particularly formation of trihalomethanes and haloacetic acids, use of this disinfectant can lead to conditions where microbiological growth – or nitrification – occurs in the distribution system. That's when Water Quality Technician Paul Race and his staff turned to Hach for help.

Nitrification episodes typically arise during warmer weather due to availability of free ammonia, which serves as a food source for ammonia-oxidizing bacteria. Warm weather raises the temperature of the water, which accelerates the degradation of chloramine. The result of this is the release of the combined ammonia, and a decrease in disinfectant residual. The warmer water temperature, combined with water-quality changes, create an environment that encourages microbial growth.