540 - Turbidity Control and Optimization of Rural Water Treatment and Distribution Systems in Puerto Rico

The Surface Water Treatment Rule (SWTR) requires all public surface-water systems (PSWs) to provide potable water with a minimum treatment consisting of filtration followed by chlorine disinfection. However, PSWSs in rural areas, have reported health-based violations of the SWTR. Non-compliance of health-based regulations is of great concern. Geographic, economic, and technical constraints create a critical problem for rural communities because without external resources it may be impossible for these communities to comply with federal drinking water regulations.
Puerto Rico has about 247 public water systems outside of Puerto Rico Aqueduct and Sewer Authority (PRASA) control. Many of these systems use source waters that are contaminated by human and animal wastes but only about half use chlorination and very few use filtration. Thus, there is a very clear need for a multi-barrier approach to provide safe water and improve the health of individuals living in communities served by the non-PRASA systems.
One of USEPA’s primary “Science-Related Issues of Importance” is finding low cost options for “Drinking Water Treatment Technologies for Small Communities”. An issue with filtration system is the potential for the filtration units to plug during high-turbidity events caused by rainfall. Such events can happen unexpectedly and can result in damage that can require significant cleaning and backwashing to return to operational use. The required effort frequently results in the community abandoning the filtration systems and bypassing the water directly to the distribution system thus endangering human health and causing a violation of the SWTR. Systems are generally gravity-fed and there is typically no electrical power or cellular service available. This project designed and implemented a low-cost solar-powered control system that would shutoff the water flow during high-turbidity events as well as provide a means of backwashing a set of gravel prefilters using filtered water. The project is also implementing a notification system that would use a mesh-network system to access the nearest line-of-sight cell phone location to send out text messages when the valves close or open.