Company lists · Data refreshed September 2026

Top 25 Wastewater engineering and design firms based in the United States

Name: Wastewater engineering and design firms based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 19, 2026 3,033 companies tracked

RevenueBase identified 3,033 wastewater engineering and design firms headquartered in the United States as of September 2026 and tracks 139,060 professional contacts across them, including 67,274 with verified work emails. Houston is the largest hub.

This list covers wastewater engineering and design firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 19, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 19, 2026 86% judged on-target in blind review

3,033Companies

139,060Contacts tracked

67,274Verified emails

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The 25 largest wastewater engineering and design firms based in the United States

Ranked by team size

Top 25 of 3,033 wastewater engineering and design firms based in the United States, ranked by team size, largest first. Data refreshed Sep 19, 2026. RevenueBase Smart Search rates how each company's information relates to wastewater engineering and design firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Tetra Tech	Partial evidence	Pasadena, CA, United StatesHQ checked Sep 19, 2026	10001+	12,999 contacts →
	Partial evidence “Tetra Tech is the leader in water, environment and sustainable infrastructure, providing high-end technical and engineering services for projects worldwide.” Source: RevenueBase Database · checked Sep 19, 2026
2	CDM Smith	Indirect evidence	Boston, MA, United StatesHQ checked Sep 19, 2026	5,001-10,000	7,527 contacts →
	Indirect evidence “CDM Smith is shaping what’s next, now, with world class solutions in water, environment, transportation and energy to public and private clients worldwide.” Source: RevenueBase Database · checked Sep 19, 2026
3	Terracon	Partial evidence	Olathe, KS, United StatesHQ checked Sep 19, 2026	5,001-10,000	6,113 contacts →
	Partial evidence “Terracon is a 100 percent employee-owned consulting engineering firm providing quality services to clients.” Source: RevenueBase Database · checked Sep 19, 2026
4	STV	Indirect evidence	New York, NY, United StatesHQ checked Sep 19, 2026	1,001-5,000	3,556 contacts →
	Indirect evidence “STV offers professional services for the infrastructure that powers our lives.” Source: RevenueBase Database · checked Sep 19, 2026
5	Brown And Caldwell	Indirect evidence	Walnut Creek, CA, United StatesHQ checked Sep 19, 2026	1,001-5,000	2,473 contacts →
	Indirect evidence “Headquartered in Walnut Creek, Calif, Brown and Caldwell is an employee-owned firm with 2,100+ professionals serving clients locally and globally from 52 locations.” Source: RevenueBase Database · checked Sep 19, 2026
6	Geosyntec Consultants	Partial evidence	Boca Raton, FL, United StatesHQ checked Sep 19, 2026	1,001-5,000	2,393 contacts →
	Partial evidence “Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural…” Source: RevenueBase Database · checked Sep 19, 2026
7	Civil & Environmental Consultants, INC	Indirect evidence	Moon Township, PA, United StatesHQ checked Sep 19, 2026	1,001-5,000	2,145 contacts →
	Indirect evidence “Civil & Environmental Consultants, Inc.(CEC) provides comprehensive market-oriented consulting services that advance the strategic business objectives of its clients.” Source: RevenueBase Database · checked Sep 19, 2026
8	Olsson	Strong evidence	Lincoln, NE, United StatesHQ checked Sep 19, 2026	1,001-5,000	2,108 contacts →
	Strong evidence “Olsson is an engineering firm made up of people who craft expert solutions and designs that improve communities.” Source: RevenueBase Database · checked Sep 19, 2026
9	Hazen And Sawyer	Indirect evidence	New York, NY, United StatesHQ checked Sep 19, 2026	1,001-5,000	2,100 contacts →
	Indirect evidence “As Hazen marks 75 years, we celebrate a legacy of absolute commitment to our clients while delivering the best technical work available anywhere.” Source: RevenueBase Database · checked Sep 19, 2026
10	Carollo Engineers	Partial evidence	Walnut Creek, CA, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,718 contacts →
	Partial evidence “For more than 90 years, Carollo Engineers has been dedicated exclusively to water and wastewater solutions.” Source: RevenueBase Database · checked Sep 19, 2026
11	Bowman Consulting	Partial evidence	Reston, VA, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,666 contacts →
	Partial evidence “Headquartered in Reston, Virginia, Bowman is a national engineering services firm delivering infrastructure solutions to customers who own, develop and maintain the built…” Source: RevenueBase Database · checked Sep 19, 2026
12	CHA Consulting, INC	Strong evidence	Albany, NY, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,639 contacts →
	Strong evidence “CHA Consulting, Inc.(CHA) is an innovative, full-service engineering, design, consulting, and program/construction management firm providing a wide range of technology-enhanced…” Source: RevenueBase Database · checked Sep 19, 2026
13	GEI Consultants, INC	Indirect evidence	Woburn, MA, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,604 contacts →
	Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026
14	Garver	Strong evidence	North Little Rock, AR, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,499 contacts →
	Strong evidence “Founded in 1919, Garver is an employee-owned engineering, planning, and environmental services firm focused on aviation, transportation, buildings, federal, water and wastewater…” Source: RevenueBase Database · checked Sep 19, 2026
15	Freese And Nichols	Partial evidence	Fort Worth, TX, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,496 contacts →
	Partial evidence “Freese and Nichols is a professional planning, consulting and engineering firm serving clients across the United States.” Source: RevenueBase Database · checked Sep 19, 2026
16	Ulteig	Strong evidence	Fargo, ND, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,362 contacts →
	Strong evidence “Ulteig delivers comprehensive design engineering, program management and technical and field services that strengthen infrastructure vital to everyday life.” Source: RevenueBase Database · checked Sep 19, 2026
17	Volkert, INC	Partial evidence	Mobile, AL, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,199 contacts →
	Partial evidence “Volkert’s history began in 1925 when it was founded in New Orleans as Doullut & Erwin to provide waterfront and heavy construction services, as well as airport design services…” Source: RevenueBase Database · checked Sep 19, 2026
18	Apex Companies	Indirect evidence	Rockville, MD, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,137 contacts →
	Indirect evidence “Who is Apex?” Source: RevenueBase Database · checked Sep 19, 2026
19	Woodard & Curran	Strong evidence	Portland, ME, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,060 contacts →
	Strong evidence “Woodard & Curran is more than just a consulting firm – we are an employee-owned integrated science, engineering, design-build, and operations company specializing in water and…” Source: RevenueBase Database · checked Sep 19, 2026
20	WSB	Indirect evidence	Minneapolis, MN, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,053 contacts →
	Indirect evidence “Forge ahead.” Source: RevenueBase Database · checked Sep 19, 2026
21	Garney Construction	Partial evidence	North Kansas City, MO, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,009 contacts →
	Partial evidence “Garney Construction is a national leader in water and wastewater construction.” Source: RevenueBase Database · checked Sep 19, 2026
22	Inframark	Indirect evidence	Horsham, PA, United StatesHQ checked Sep 19, 2026	1,001-5,000	973 contacts →
	Indirect evidence “As an Azuria owned company, Inframark is a widely recognized leader in Water Infrastructure Operations and Infrastructure Management Services.” Source: RevenueBase Database · checked Sep 19, 2026
23	GAI Consultants, INC	Partial evidence	Homestead, PA, United StatesHQ checked Sep 19, 2026	501-1,000	964 contacts →
	Partial evidence “Transforming ideas into reality® since 1958, GAI Consultants is an engineering, planning, and environmental consulting firm that provides customized solutions and local expertise…” Source: RevenueBase Database · checked Sep 19, 2026
24	ATC Group Services LLC	Indirect evidence	Lafayette, LA, United StatesHQ checked Sep 19, 2026	1,001-5,000	865 contacts →
	Indirect evidence “ATC Group Services LLC is now Atlas.” Source: RevenueBase Database · checked Sep 19, 2026
25	DUDEK	Partial evidence	Encinitas, CA, United StatesHQ checked Sep 19, 2026	501-1,000	795 contacts →
	Partial evidence “Dudek is an environmental, planning, and engineering consulting firm.” Source: RevenueBase Database · checked Sep 19, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: wastewater engineering and design firms. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names wastewater engineering and design firms.
Partial evidence: Its own public description names part of wastewater engineering and design firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name wastewater engineering and design firms. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 3,033 wastewater engineering and design firms based in the United States

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Wastewater engineering and design firms based in the United States at a glance

As of Sep 19, 2026

48.4%Verified-email coverage

45.8Average contacts per company

11-50Median size (employees)

2.8%Largest-city concentration · Houston

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

1,270

11-50

1,120

51-200

439

201-500

120

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 3,033 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among wastewater engineering and design firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “wastewater engineering and design firms”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names wastewater engineering and design firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among wastewater engineering and design firms, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 67,274 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 19, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Wastewater engineering and design firms by metro

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names wastewater engineering and design firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many wastewater engineering and design firms are there based in the United States?

RevenueBase identified 3,033 wastewater engineering and design firms headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Tetra Tech, headquartered in Pasadena, tops this list with the largest team on record.

Which city has the most wastewater engineering and design firms?

Houston leads with 84 headquartered companies, followed by Austin (48) and Miami (27).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 67,274 verified decision-maker contacts tracked across these 3,033 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 19, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.