Strategies to minimize sediment contamination and transport in distribution systems
Citation:
Hall, J. AND J. Szabo. Strategies to minimize sediment contamination and transport in distribution systems. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-23/069, 2024.
Impact/Purpose:
Drinking water storage tanks serve an important role in water distribution systems worldwide. They are not only used for emergency water supply needs such as firefighting emergencies, power outages, and water main breaks, but also used to maintain and minimize pressure fluctuations within the distribution system. The infrequent use of the water within the drinking water storage tanks can lead to lead to deterioration of the disinfectants within the water and subsequent biological, or radiological issues can develop. Another potential problem is the buildup of sediments within a drinking water storage tank. These sediments can be from the corrosion of the tank itself or introduced somewhere else in the system and can increase disinfectant demand or provide a haven for microbials to grow. Fortunately, steps can be taken to reduce the effects of sediments within drinking water storage tanks. This report looks to aggregate knowledge and research on sediments within drinking water storage tanks and highlight key ideas within them that will allow for system operators to better reduce the chance of water quality degradation.
Description:
Drinking water storage tanks serve several important functions, which include but are not limited to providing an adequate water supply in the case of firefighting emergencies, power outages, water main breaks, or other system failures. The water level elevation in storage tanks helps to 1) maintain water distribution system pressure, and 2) minimize fluctuations caused by changes in customer demand or system operating conditions. One problem, however, is that the drinking water quality in finished water storage tanks can deteriorate over time and present biological, physical, and chemical water quality issues, some with potential health impacts. For example, chlorine or other disinfectant residuals may decrease, disinfection by-product (DBP) levels may increase, and taste and odor issues can develop. In addition, pH can increase, tank materials can corrode, and iron and manganese can precipitate (Mays, 2001). Lastly, sediments, which accumulate on the tank floor, can increase disinfectant demand, microbial growth, DBP formation, and turbidity (USEPA, 2002).