Reverse Osmosis (RO) Water Treatment Facility

RO Interior

The PSD’s Reverse Osmosis (RO) Water Treatment Facility provides more than 40 percent of our water supply. Reverse osmosis is a pressure-driven membrane separation process that removes ions, salts, and other dissolved solids and nonvolatile organic compounds. The separation capability of the process is controlled by the diffusion rate of solutes through a barrier and by sieving. The membranes are comprised of synthetic polymers similar to Nylon. The polymers are permeable to water but reject particulate matter such as salts and other minerals. The process produces fresh drinking water and yields a concentrate of the rejected solids.

The PSD’s RO Plant, located across U.S. 278 from Windmill Harbour, began operations in April 2009. It provides customers with 3 million gallons of fresh water a day, about half of the average daily demand for water. In 2013, the PSD began preparations to expand the plant’s production to 4 million gallons a day. The RO Plant’s construction was necessary to replace water supply lost to saltwater intrusion. The plant uses state-of-the-art filtration to produce a very high-quality water. In fact, it’s the same process used to produce many brand-name bottled waters and other beverages. The RO plant is expandable to provide 6 million gallons of water a day. The PSD has the capability to expand the plant in 1-MGD (million gallons per day) increments, thereby allowing the plant’s capacity to increase as it is needed to replace water supply lost as a result of saltwater intrusion.

The RO Plant is fed by three raw water wells drilled into the 600-foot-deep Middle Floridan Aquifer. The wells are pumped at a rate of approximately 1,500 gallons per minute (gpm) and the plant operates 24/7. The groundwater in this aquifer is brackish and requires filtration in the RO Plant. For every 3 MGD of drinking water produced by the plant, 1 MGD of concentrate is diffused into the saltwater background of Skull Creek via a pipeline at the end of Jenkins Island Road. Scientific research and monitoring has shown that the Middle Floridan Aquifer is a very abundant and long-term source of water for the island’s future.