<P> A publicly owned treatment works (POTW) is a term used in the United States for a sewage treatment plant that is owned, and usually operated, by a government agency . In the U.S., POTWs are typically owned by local government agencies, and are usually designed to treat domestic sewage and not industrial wastewater . </P> <P> The term is used extensively in U.S. water pollution law (i.e. the Clean Water Act), regulations and programs . Many POTWs were established or expanded with grants or low - interest loans from the U.S. Environmental Protection Agency (EPA). </P> <P> There are over 16,000 POTWs in the U.S., serving 75 percent of the total population . The remainder of the population is served by decentralized or private septic systems . The POTWs treat 32 billion US gallons (120 gigalitres) of wastewater every day . Most POTWs are required to meet national secondary treatment standards . </P>

How many wastewater treatment plants are there in the us