The blue and grey water footprint of construction materials: Steel, cement and glass

Numerous studies have been published on water footprints (WFs) of agricultural products, but much less on WFs of industrial products. The latter are often composed of various basic materials. Already the basic materials follow from a chain of processes, each with its specific water consumption (blue WF) and pollution (grey WF). We assess blue and grey WFs of five construction materials: chromium-nickel unalloyed steel, unalloyed steel, Portland cement (CEM I), Portland composite cement (CEM II/B) and soda-lime glass. Blue and grey WFs are added up along production chains, following life cycle inventory and WF accounting procedures. Steel, cement and glass have WFs dominated by grey WFs, that are 20–220 times larger than the blue WFs. For steel, critical pollutants are cadmium, copper and mercury; for cement, these are mercury or cadmium; for glass, suspended solids. Blue WFs of steel, cement and glass are mostly related to electricity use.