NAICS Code 221310 — Water Supply and Irrigation Systems

National Industry in the official 2022 North American Industry Classification System (U.S. Census Bureau). It is the only national industry under 22131 (Water Supply and Irrigation Systems).

Code	221310
Title	Water Supply and Irrigation Systems
Level	National Industry (6-digit)
Edition	NAICS 2022 edition
SBA size standard	$41 million in average annual receipts

Official definition (2022 NAICS)

This industry comprises establishments primarily engaged in operating water treatment plants and/or operating water supply systems. The water supply system may include pumping stations, aqueducts, and/or distribution mains. The water may be used for drinking, irrigation, or other uses.

Cross-References.

Is a business under 221310 "small"?

Under the SBA size standards (13 CFR 121.201, effective March 17, 2023), a business classified in NAICS 221310 qualifies as a small business if it does not exceed $41 million in average annual receipts. Small-business status determines eligibility for federal set-aside contracts, SAM.gov certifications and SBA loan programs — receipts are averaged over the latest 5 fiscal years.

Where 221310 sits in the hierarchy

Level	Code	Title
Sector	22	Utilities
Subsector	221	Utilities
Industry Group	2213	Water, Sewage and Other Systems
NAICS Industry	22131	Water Supply and Irrigation Systems
National Industry	221310	Water Supply and Irrigation Systems

Related SIC codes

Via the official U.S. Census concordance (1987 SIC ↔ NAICS), shown only where the industry definition is unchanged in NAICS 2022.

SIC code	Title
4941	Water Supply
4971	Irrigation Systems

Data: official 2022 NAICS structure, descriptions and Census concordances, U.S. Census Bureau — U.S. government works in the public domain (17 U.S.C. §105). Suggested reference, not an official determination.