As a leading U.S. contractor in water, wastewater, and industrial water construction projects, we are committed to delivering maximum value to clients and their communities. MWH history dates to the early 19th century and features some of the world’s most groundbreaking water and wastewater innovations as well as specialization in client-focused collaborative delivery methods. The MWH family includes Slayden Constructors in the Pacific Northwest and Methuen Construction Company in the Northeast.