U.S. Water was recently contracted to perform sand filter rehabilitation on all four sand filters at the South County Advanced Wastewater Treatment Plant in Hillsborough County. The County started finding issues with the filters, needing to perform excessive backwashes, meaning reversing the flow and increasing the velocity at which water passes back through the filters, unclogging the filters. U.S. Water started the rehabilitation process early on in April 2021, performing one filter at a time to keep the plant up and running smoothly. The process consists of removing all media from the filter, removing the underdrain, inspecting all air scourers, replacing the underdrain, and installing new media. One challenge experienced with this project has been examining and replacing the air sources due to erosion. There have been about 12 air source replacements due to erosion damage so far. The team has been pulling samples before and after each filter rehabilitation to see the changes and improvements. Currently, on the verge of completing filter number three, the testing numbers have been going up in the system, showing positive results for the County.