Wastewater generated in Rocky Hill is treated at the Rocky Hill Water Pollution Control Facility. When it rains, large amounts of stormwater enter the sanitary sewer and overwhelm the facility’s ability to treat the water. This can then cause basement backups and discharges of raw sewage to local waterways. On dry days, the facility treats an average 5.5 million gallons of sewage, but can receive in excess of 20 million gallons of sewage a day when it rains, as stormwater finds its way into Rocky Hill's 87 miles of sewer pipes - half of which are more than 40 years old. In addition, when the Connecticut River floods, high river levels inundate the sewer system. Homeowner drainage flows from down spouts, basement sump pumps and yard drains connected to the sewer system also contribute to the problem.