The global demand for water and energy is projected to grow, but there likely will be significant constraints in our ability to keep meeting it. These constraints will be imposed partly by the interdependence between water, energy, and climate change. If left unchecked, these connections can exacerbate water and energy shortages and aggravate climate change impacts: Energy is used to supply and treat water; moreover, emissions from energy generation contribute to climate change, which affects water supplies and increases the demand for energy to sustain Earth's growing population and economy. The linkage between water and energy can offer opportunities for better meeting expected demand while minimizing damage from shortages of either. This article focuses on the technological and engineering aspects of various connections in the water-energy nexus where advancements can enable greater supply of one or both. It also outlines the benefits and challenges associated with each connection.