Key TakeawaysHouston's Northeast Water Purification Plant expansion project is required to comply with subsidence district rules for conversion from groundwater to surface water supply.Innovative solutions for the expanded plant include two coagulation recipes to treat water from Lake Houston; treatment with chlorine dioxide, ozone, and biological filtration; and enhanced residuals treatment.A progressive design–build approach—used for the largest project of this kind presently underway in North America—maximized stakeholder involvement.