Carollo Engineers is a prominent environmental engineering firm based in the U.S., specializing in water and wastewater solutions. Founded in Phoenix, Arizona, in 1933, the company has expanded to over 1,100 employees across 49 offices nationwide. Carollo focuses on the planning, design, construction, and management of water and wastewater facilities, emphasizing a holistic approach that considers the impact on families, communities, and ecosystems.

The firm offers a range of services, including feasibility studies, planning, design and engineering of treatment plants, and construction management. They utilize advanced technologies like 3D design and Building Information Modeling (BIM) to enhance project delivery. Carollo Engineers provides various water treatment systems, including those for drinking water, wastewater, and specialized industrial applications. Their commitment to quality engineering and environmental stewardship supports their mission of delivering sustainable water infrastructure that benefits both ecosystems and communities.