NAICS 221320 Quarterly Industry Report
Sewage Treatment Facilities
Comprehensive industry research for valuation professionals, business owners, buyers, and lenders
NAICS Code: 221320Sector: Utilities (22)Updated: Q1 2026
About This Report
This industry profile for Sewage Treatment Facilities (NAICS 221320) draws on data from the Bureau of Labor Statistics[6], U.S. Census Bureau, and SBA size standards database[7]. Published by Fair Market Value and updated quarterly, it provides valuation professionals, water utility analysts, and business brokers with current market data. The editorial analysis reflects the independent assessment of FairMarketValue.com's research team, with all quantitative claims sourced to publicly verifiable databases.
Industry Snapshot
Key metrics for the sewage treatment facilities industry.
Industry Definition & Overview
Sewage Treatment Facilities (NAICS 221320) encompasses establishments primarily engaged in operating sewer systems or sewage treatment facilities that collect, treat, and dispose of waste per the U.S. Census Bureau[5]. This classification covers wastewater collection through sewer networks, preliminary and primary treatment to remove solids, secondary biological treatment, advanced tertiary treatment, and biosolids management. Treated effluent is discharged to receiving waters under National Pollutant Discharge Elimination System (NPDES) permits.
About 386 private-sector companies employ roughly 7,050 workers per the Bureau of Labor Statistics[6]. Most sewage treatment infrastructure in the United States is owned and operated by municipal governments, making the private-sector establishment count a small fraction of total facilities. Over 16,000 publicly owned treatment works (POTWs) operate nationally, serving about 75 percent of the U.S. population through centralized sewer systems. Private operators include contract operations firms that manage publicly owned plants and small investor-owned wastewater utilities.
Per the SBA Table of Size Standards[7], the size standard is $35.0 million in average annual receipts. EPA's Clean Water Act establishes water quality standards and NPDES permitting for all point source discharges. Combined sewer overflow (CSO) control and sanitary sewer overflow (SSO) prevention drive billions in annual capital investment at aging systems. Nutrient removal requirements for nitrogen and phosphorus have increased treatment complexity and costs at facilities discharging to impaired waterways. Biosolids management through land application, incineration, or landfill disposal represents a growing operational challenge as regulations tighten around PFAS contamination in treated sludge.
What's Included in This Industry
- Wastewater collection sewer system operations
- Primary and secondary treatment processes
- Advanced tertiary treatment and nutrient removal
- Biosolids processing and disposal
- NPDES permit compliance and monitoring
- Pump station operations and maintenance
- Sewer system rehabilitation and repair
- Industrial pretreatment program management
- Effluent water quality testing
- Combined sewer overflow control
NAICS Classification Hierarchy
| Level | Description | Code |
|---|---|---|
| Sector | Utilities | 22 |
| Subsector | Utilities | 221 |
| Industry Group | Water, Sewage and Other Systems | 2213 |
| NAICS Industry | Sewage Treatment Facilities | 22132 |
| National Industry | Sewage Treatment Facilities | 221320 |
Related NAICS Codes
| Code | Description | Relationship |
|---|---|---|
| 221310 | Water Supply and Irrigation Systems | Water Supply and Irrigation Systems operate the clean water side of the utility cycle, with many integrated utilities managing both water treatment and wastewater treatment under combined operations |
| 237110 | Water and Sewer Line and Related Structures Construction | Water and Sewer Line Construction builds collection sewers, trunk lines, and treatment plant structures that wastewater facilities need for capacity expansion and system rehabilitation |
| 541330 | Engineering Services | Engineering Services design treatment plant upgrades, nutrient removal systems, and collection sewer rehabilitation projects during capital improvement programs mandated by permit requirements |
| 562991 | Septic Tank and Related Services | Septic Tank Services provide decentralized wastewater disposal in areas without sewer connections, with septage from pumped tanks often delivered to municipal treatment plants for processing |
| 562998 | All Other Miscellaneous Waste Management Services | All Other Miscellaneous Waste Management includes sewer cleaning services that maintain collection system infrastructure, removing debris and blockages from pipes that feed treatment plants |
| 541620 | Environmental Consulting Services | Environmental Consulting Services perform water quality assessments, permit applications, and compliance support for treatment facilities meeting Clean Water Act discharge requirements |
Geographic Concentration
Top states by share of national establishments.
| # | State | % Est. | Total Est. |
|---|---|---|---|
| 1 | Texas | 11.2% | 62 |
| 2 | New York | 9.6% | 53 |
| 3 | Pennsylvania | 8.2% | 45 |
| 4 | California | 6.3% | 35 |
| 5 | Florida | 6.0% | 33 |
| 6 | Louisiana | 3.8% | 21 |
| 7 | Indiana | 3.6% | 20 |
| 8 | Illinois | 3.6% | 20 |
| 9 | North Carolina | 3.3% | 18 |
| 10 | Missouri | 2.9% | 16 |
% Of Establishments
0%
11%
Source: County Business Patterns, U.S. Census Bureau[3]
SBA Lending Summary
8
Total SBA Loans
$1.2M
Total Loan Volume
$150K
Average Loan Size
10 yrs
Average Loan Term
10.25%
Average Interest Rate
56
Jobs Supported
Source: SBA 7(a) Program Data, U.S. Small Business Administration — FY 2025[4]
Key Insight: Per the SBA Table of Size Standards[7], Sewage Treatment Facilities (NAICS 221320) has a size standard of $35.0 million in average annual receipts for federal contracting purposes. SBA 7(a) loans[8] support treatment upgrades, sewer rehabilitation, and working capital for qualifying operators. Private contract operations firms managing municipal treatment plants represent a growing small business segment. Additionally, 504/CDC loans[9] provide long-term, fixed-rate financing for major fixed assets such as real estate and equipment.
Top SBA Lenders
| # | Lender | Loans | Volume | Avg Loan |
|---|---|---|---|---|
| 1 | Northeast Bank | 8 | $1.2M | $150K |
Frequently Asked Questions
Common questions about this industry.
What types of businesses operate sewage treatment facilities?
Most facilities are municipally owned, but about 386 private companies employ roughly 7,050 workers per the U.S. Census Bureau[5]. Private operators include contract management firms running public plants and small investor-owned wastewater utilities.
How many treatment facilities exist in the U.S.?
Over 16,000 publicly owned treatment works operate nationally, serving about 75 percent of the population per the Bureau of Labor Statistics[6]. The private-sector count of 386 firms represents contract operators and investor-owned systems rather than total facility count.
What is the SBA size standard for Sewage Treatment?
Per the SBA Table of Size Standards[7], NAICS 221320 has a size standard of $35.0 million in average annual receipts. This determines eligibility for SBA loans, federal contracting set-asides, and small business programs.
What NAICS codes are related to sewage treatment?
Related codes include NAICS 221310 (Water Supply), NAICS 237110 (Sewer Construction), NAICS 541330 (Engineering), NAICS 562991 (Septic Services), and NAICS 541620 (Environmental Consulting) per the U.S. Census Bureau[5].
How are treatment facilities regulated?
EPA's Clean Water Act establishes NPDES permitting for point source discharges. State agencies issue permits setting specific discharge limits for pollutants including biochemical oxygen demand, suspended solids, nitrogen, and phosphorus.
What activities are included in NAICS 221320?
Core activities include sewer collection, primary and secondary treatment, nutrient removal, biosolids processing, NPDES compliance, pump station operations, sewer rehabilitation, pretreatment programs, water quality testing, and overflow control per the U.S. Census Bureau[5].
Can sewage treatment businesses get SBA loans?
Yes, firms meeting the $35.0 million size standard qualify for SBA 7(a) loans[8] covering treatment upgrades, sewer rehabilitation, and working capital. Private contract operations companies are the most common small business applicants.
What is driving capital investment in wastewater?
Combined sewer overflow control, nutrient removal mandates, aging infrastructure replacement, and PFAS contamination in biosolids drive billions in annual capital spending per the Bureau of Labor Statistics[6]. Many systems built in the mid-20th century require major rehabilitation to meet current regulatory standards.
Sources & References
Government datasets and editorial sources used in this report.
- [1]U.S. Bureau of Labor Statistics, Quarterly Census of Employment and Wages bls.gov
- [2]U.S. Census Bureau, Economic Census census.gov
- [3]U.S. Census Bureau, County Business Patterns census.gov
- [4]U.S. Small Business Administration, SBA 7(a) Loan Program Data data.sba.gov
- [5]U.S. Census Bureau census.gov
- [6]Bureau of Labor Statistics bls.gov
- [7]SBA Table of Size Standards sba.gov
- [8]SBA 7(a) loans sba.gov
- [9]504/CDC loans sba.gov
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