Water and Sewer Line and Related Structures Construction (NAICS 23711)

A rollup primer for public-market and private investors

Read this first — single-child level. In the North American Industry Classification System (NAICS), the five-digit industry 23711 contains exactly one six-digit national industry: 237110, of the same name. At this level of the taxonomy the two are effectively identical — the same firms, the same receipts, the same economics. This page is a short pointer: it states this level's own ground-truth federal figures and explains where value concentrates, then sends you to the 237110 primer for full detail on companies, contract mechanics, demand drivers, regulation, and how to invest. [1]

1. Overview

This is the industry that physically builds, rehabilitates, and replaces the pipes, mains, pumps, tanks, and treatment plants that move drinking water into communities and carry sewage and stormwater away. It is heavy-civil construction — crews, excavators, and pipe in the ground — not the operation of the water utility itself, and not the making of the pipe and valves. It is a project-based business whose customer base is overwhelmingly government, whose in-ground assets are old, and whose replacement bill is enormous and increasingly mandated by federal rule. [1]

Because NAICS 23711 has only one child, everything true of that child is true here. The reason to look at this five-digit level at all is that it is where U.S. statistical agencies publish "water and sewer construction" as a single line — the number you would cite for the industry as a whole.

2. What's inside — and why this level equals its one child

NAICS is hierarchical: sector (2-digit) → subsector (3-digit) → industry group (4-digit) → NAICS industry (5-digit) → national industry (6-digit). Most five-digit industries split into several six-digit children with distinct economics. 23711 does not. It has a single child:

So the five-digit "industry" and the six-digit "national industry" describe the same set of establishments. There is no sub-mix to weigh, no segment to break out — the rollup is the child. For scope (what counts as 237110 versus the adjacent pipeline, highway, plumbing, and utility-operation codes), see Section 2 of the 237110 primer. [1]

3. How big it is (this level's figures)

These are the federal statistics for NAICS 23711 — identical to 237110 because it is the only child. All figures come from our ground-truth stats file for this level.

Two quick reads. Average revenue per firm is only about $5.5 million ($56.9 billion ÷ 10,380) — a small-business industry by any measure. And the concentration figures (CR4 of 4.2%, HHI near 11 on a 0–10,000 scale) mark this as one of the most fragmented industries in the construction economy. [3][4]

Undercount caveat — read this. These figures capture private construction contractors with employees only. They miss two large pools of activity: government force-account work (municipal public-works and utility crews who build and repair their own lines, counted as government employment, not here), and nonemployer operators (the self-employed and very small firms excluded from County Business Patterns). Because ownership is dominated by small and individually run firms, and because the demand is funded almost entirely by public budgets, true water-and-sewer construction activity in the economy is meaningfully larger than the $56.9 billion of measured private-contractor receipts. [2][3]

4. Investable universe — where the value sits

There is no large, pure-play public company whose revenue cleanly equals this industry; the work is intensely local, mostly private and municipal. Public-market exposure is therefore indirect, and it is identical to the child's because the level is the child. In brief, value concentrates across four adjacent groups:

• Diversified heavy-civil contractors (water is a minority of revenue): MasTec (MTZ), Sterling Infrastructure (STRL), Primoris (PRIM), Granite (GVA), Southland Holdings (SLND — the most water-concentrated, but small).
• Engineering / program management: AECOM (ACM), Tetra Tech (TTEK), Jacobs (J).
• Products, equipment, distribution (cleaner "water" exposure, but not contractor economics): Core & Main (CNM), Mueller Water Products (MWA), Xylem (XYL), NWPX Infrastructure (NWPX).
• Regulated water utilities (asset owners / capital-spending proxies): American Water Works (AWK), Essential Utilities (WTRG).
• Private and private-equity-backed players: Azuria Water Solutions (formerly Aegion; owner of the Insituform trenchless brand), plus employee- and family-owned platforms with real scale but no public listing — Garney, Kiewit, Michels, Black & Veatch, and others.

Full tables, tickers, and the water-exposure notes are in Section 4 of the 237110 primer. [2][3][4]

5. How the money works

Contractor economics, not utility economics. Owners make money by winning projects and executing them profitably — the contractor supplies labor and equipment, buys materials, completes the work, and collects progress payments. The metrics that matter are funded backlog and book-to-bill; the margin risk is fixed-price / unit-price exposure to pipe, steel, cement, fuel, labor, weather, and subsurface surprises; and cash lags reported revenue because of retainage, mobilization, and slow public-owner payments. Rehabilitation and repair — especially trenchless relining — is the recurring, higher-margin, more differentiated slice. Do not value these contractors like the rate-regulated utilities that appear in the investable universe. See Section 5 of the 237110 primer. [2]

6. Demand drivers

Aging pipe (much of it 50–100+ years old), a roughly $1.25 trillion combined 20-year capital need (EPA: ~$625 billion drinking water, ~$630 billion wastewater/stormwater), a federal lead-service-line replacement mandate, emerging PFAS ("forever chemicals") treatment work, and the Infrastructure Investment and Jobs Act (IIJA) funding surge routed through the State Revolving Funds. The need is durable and increasingly non-discretionary; the timing is lumpy and gated by local budgets. Full detail and citations are in Section 6 of the 237110 primer.

7. Regulation

Regulation both creates the work and sets the build-to rules: the Safe Drinking Water Act (SDWA) and Clean Water Act (CWA), overflow consent decrees, the Lead and Copper Rule Improvements (LCRI), the State Revolving Funds and Water Infrastructure Finance and Innovation Act (WIFIA) loan programs, Build America, Buy America (BABA) and American Iron and Steel (AIS) sourcing rules, Davis-Bacon prevailing wages, and Occupational Safety and Health Administration (OSHA) trenching standards. See Section 7 of the 237110 primer.

8. Consolidation

Near-atomistic: CR4 of 4.2%, HHI near 11 — no firm above roughly 5% share. [4] Work stays local because crews, equipment, permits, bonding, and subsurface knowledge travel poorly. The consolidation that happens runs on two tracks — diversified public contractors bolting on regional water builders, and private-equity roll-ups (the Azuria model) — but the long tail of thousands of small contractors is durable. Section 8 of the 237110 primer covers this in full.

9. Risks

The single biggest swing factor is the funding cliff — demand is a government budget, and much IIJA water money is being obligated through roughly 2026. Add fixed-price margin risk, input-cost inflation, skilled-labor scarcity, cash-conversion strain on small firms, interest-rate / municipal-budget sensitivity, and regulatory whipsaw (notably unsettled PFAS standards). See Section 9 of the 237110 primer.

10. How to invest and the outlook

Because 23711 equals 237110, the investing playbook is the same: start with exposure, not the ticker — for any public name, ask how much revenue is really water, and whether it is self-performed construction, design/engineering, equipment, or utility rate recovery. Public routes run through diversified contractors, engineering firms, product/distribution names, regulated utilities, and thematic water ETFs (e.g., PHO, FIW, CGW — check current holdings). Private routes run through private equity and infrastructure funds, private credit, and the municipal bonds that fund the projects.

Outlook. A multi-decade replacement supercycle with unusually long, partly mandated demand visibility, but an uneven investment outcome — execution, funding timing, labor productivity, and cash conversion separate winners from losers. The tailwind is strong and durable; the cleanest way to own it is indirect. For the complete treatment — company tables, contract mechanics, the full demand and regulation sections, diligence checklist, and forward judgment — see the NAICS 237110 primer, of which this five-digit level is a one-to-one rollup.

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Sources

1. U.S. Census Bureau, "2022 NAICS Definition: 237110 Water and Sewer Line and Related Structures Construction" (the sole child of five-digit industry 23711). https://www.census.gov/naics/?details=237110&year=2022
2. U.S. Census Bureau, County Business Patterns: 2023 (establishments, employment, annual and first-quarter payroll for NAICS 237110 = 23711). https://www.census.gov/data/datasets/2023/econ/cbp/2023-cbp.html
3. U.S. Census Bureau, 2022 Economic Census — Construction Summary Statistics (receipts and firm count for NAICS 237110 = 23711). https://data.census.gov/table/ECNBASIC2022.EC2223BASIC
4. U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms (CR4/CR8/CR20/CR50 and HHI for NAICS 237110 = 23711). https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN

Company, funding, and regulation citations – are carried in full by the child primer (NAICS 237110); this rollup page cites only the federal figures specific to the 23711 level.