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.
how many wastewater treatment plants are there in the us
over 16,000