NAICS 221310:
Water Supply and Irrigation Systems
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.
Water supply systemsWater treatment plantsIrrigation system operation+4 examples
Water filtration plant operationWater treatment and distributionWater distribution for irrigationWater distribution (except irrigation)
Matching SIC code: 4941 Water Supply (also 4971 Irrigation Systems)
Where it sits
- 22UtilitiesSector
- 221UtilitiesSubsector
- 2213Water, Sewage and Other SystemsIndustry group
- 22131Water Supply and Irrigation SystemsNAICS industry
- 221310Water Supply and Irrigation SystemsNational industry
Largest companies with NAICS 221310
Updated Nov 9, 2026| Rank | Company | Headquarters | Employees |
|---|---|---|---|
| 1 |  American Wateramwater.com | Camden, US | 4.6K |
| 2 |  Aquaaquawater.com | Bryn Mawr, US | 3.3K |
| 3 |  EBMUDebmud.com | Oakland, US | 1.5K |
| 4 |  WSSC Waterwsscwater.com | Laurel, US | 1.4K |
| 5 |  Valley Watervalleywater.org | US | 1.1K |
| 6 |  DC Waterdcwater.com | Washington, US | 1.1K |
| 7 |  San Antonio Water Systemsaws.org | San Antonio, US | 1K |
| 8 |  Denver Waterdenverwater.org | Denver, US | 986 |
| 9 |  Las Vegas Valley Water Districtlvvwd.com | Las Vegas, US | 766 |
| 10 |  California Water Servicecalwater.com | US | 719 |
Not this code?
Similar activities the Census classifies elsewhere.
- 237110Water and Sewer Line and Related Structures ConstructionEstablishments primarily engaged in irrigation project construction (except lawn)
- 238220Plumbing, Heating, and Air-Conditioning ContractorsEstablishments primarily engaged in installing lawn sprinkler systems
- 561730Landscaping ServicesEstablishments primarily engaged in lawn irrigation services
- 445298All Other Specialty Food RetailersEstablishments primarily engaged in retailing bottled water
Questions about NAICS 221310
Which businesses use NAICS 221310?
Water supply systems, water treatment plants and irrigation system operation, and similar businesses in the Utilities sector. This industry comprises establishments primarily engaged in operating water treatment plants and/or operating water supply systems.
What SIC code matches NAICS 221310?
SIC 4941, Water Supply; SIC 4971, Irrigation Systems, from the US Census Bureau's concordance between the two systems.
How many companies have NAICS 221310?
3,609 companies with a website carry NAICS 221310 as their primary code in Crustdata's data, worldwide.
Find any company's NAICS codeType a company name or website and get its codes with their titles.
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Sign up freeCode titles, definitions, examples and SIC matches: NAICS 2022 and the Census concordances, US Census Bureau. Company counts and lists: Crustdata, companies with a website, each by its primary code, updated weekly. Employee counts are estimates.