NAICS 221320

Overview

The North American Industry Classification System (NAICS) is the federal standard for classifying business establishments to support the collection, analysis, and publication of statistics about the U.S. economy. Developed under the Office of Management and Budget with partners in Canada and Mexico, NAICS replaced SIC in 1997; the current U.S. vintage is 2022. ¹

NAICS 221320 — Sewage Treatment Facilities — comprises establishments primarily engaged in operating sewer systems or sewage treatment facilities that collect, treat, and dispose of waste. Federal statistical programs and procurement reporting use this code to identify wastewater utility operations distinct from solid waste, septic, or water-supply activities. ²

What this NAICS covers

• Operation of sewer systems that collect wastewater through permanent networks. ²
• Operation of sewage treatment plants that process and dispose of waste. ²
• End-to-end collection, treatment, and disposal of wastewater via sewer systems. ²
• Utility management of sewer networks and treatment facilities as a single activity. ²
• Provision of sewage removal services through publicly or privately operated systems. ²
• Disposal of waste as an output of sewage treatment facility operations. ²

Related NAICS and PSC codes

Type	Code	Descriptor
NAICS	56221	Waste Treatment and Disposal
NAICS	562991	Septic Tank and Related Services
PSC	Y1ND	Construction of Sewage and Waste Facilities
PSC	M1ND	Operation of Sewage and Waste Facilities

Boundaries and exclusions

• Solid or hazardous waste treatment or disposal facilities (not using sewer systems) fall under NAICS 56221; NAICS 221320 is limited to sewer systems and sewage plants. ²
• Pumping/cleaning septic tanks and cesspools are NAICS 562991, not NAICS 221320. ²
• Cleaning and rodding of sewers and catch basins are NAICS 562998, not NAICS 221320. ²
• Operating water treatment plants and water supply systems is NAICS 221310, not NAICS 221320. ²

Acquisition context

Federal Acquisition Regulation Subpart 41 includes standard specification formats for acquiring utility services, specifically listing “sewage service” among the utility types. This helps agencies structure solicitations and contracts for wastewater utility requirements aligned with NAICS 221320. ⁴

Frequently asked questions

• What activities are included in NAICS 221320?
  Establishments operating sewer systems or sewage treatment facilities that collect, treat, and dispose of waste are included. The code covers the combined activity of wastewater collection and treatment via sewer infrastructure. ²

• How does NAICS 221320 differ from NAICS 562991 and 56221?
  Septic tank pumping/cleaning is classified in NAICS 562991, while non-sewer solid or hazardous waste treatment/disposal uses NAICS 56221. NAICS 221320 is reserved for sewer systems and sewage treatment facilities. ²

• Are public sewer utilities included in published NAICS statistics?
  NAICS defines industries regardless of ownership, but the Economic Census generally excludes government-owned establishments (including public sewer utilities) from its coverage. This affects data publication, not the classification standard itself. ⁵

• Which PSCs commonly align to sewage facility work?
  The PSC Manual lists codes such as Y1ND for construction and M1ND for operation of sewage and waste facilities, used to describe procurement actions in FPDS. ⁶

Useful resources

• U.S. Census Bureau NAICS main page (official definition and tools). ¹
• 2022 NAICS Manual (authoritative industry descriptions). ²
• Census 2022 NAICS implementation timeline and adoption status. ³

References

1. U.S. Census Bureau — North American Industry Classification System (NAICS): https://www.census.gov/naics
2. U.S. Census Bureau — 2022 NAICS Manual (see 221320 Sewage Treatment Facilities): https://www.census.gov/naics/reference_files_tools/2022_NAICS_Manual.pdf
3. U.S. Census Bureau — The Census Bureau’s Implementation of the 2022 NAICS: https://www.census.gov/library/reference/code-lists/naics/2022/implementation-timeline.html
4. Federal Acquisition Regulation 41.701 — Formats for utility service specifications: https://www.acquisition.gov/far/41.701
5. U.S. Census Bureau — NAICS Codes & Understanding Industry Classification Systems (Economic Census coverage note): https://www.census.gov/programs-surveys/economic-census/year/2022/technical-documentation/code-lists/understanding-naics-redirect.html
6. Product and Service Code (PSC) Manual, April 2025 Edition — sewage and waste facilities codes (e.g., Y1ND, M1ND): https://origin-www.acquisition.gov/sites/default/files/manual/PSC%20Manual%20April%202025.pdf