The Metropolitan Sewer District of Greater Cincinnati (MSD) is a publicly-operated wastewater utility that serves about 230,000 residential and commercial users in most of Hamilton County, Ohio and parts of Butler, Clermont, and Warren counties.MSD's service area spans 290+ square miles and contains over 200,000 separate sewer connections which tie into approximately 3,000 miles of sanitary and combined sewers. MSD treats about 180 million gallons of wastewater per day.