Basic Course: Supplemental Topics (NPDES Permit 5)

Categories of NPDES Permits: POTW and Non-POTW

EPA groups NPDES permits into two categories based broadly on the type of point source:

• Publicly owned treatment works (POTW). Treatment works that are owned by a State/Tribe or municipality. This includes devices and systems used in the storage, treatment, recycling, and reclamation of municipal sewage or industrial wastes of a liquid nature.
  • POTWs can treat municipal sewage, industrial wastes, or a combination of the two.
• Non-publicly owned treatment works (non-POTW). All other facilities are non-POTWs and are often referred to as “non-municipals” or “industrials.”
  • Industrials could include privately owned treatment works, water treatment plants, concentrated animal feeding operations (CAFOs), or any manufacturing or commercial activity.

EPA divides these two categories further between major and minor facilities—a distinction that was established during early implementation of the NPDES program to help prioritize the issuing of permits.

• Major POTWs include:
  • Treatment works with design flows greater than 1 million gallons/day (MGD).
  • Other treatment works given this designation (i.e., the Regional administrator has done so, in consultation with the State/Tribal permitting authority).
• Major non-POTWs include:
  • Treatment works that score 80 or more points on the NPDES Permit Rating Worksheet.
  • Other treatment works given this designation (i.e., the Regional administrator has done so, in consultation with the State/Tribal permitting authority).
• Minor POTWs/non-POTWS include:
  • All other dischargers.