Water is a critical, but often undervalued aspect of sustainability. There is a surprising lack of awareness for water resources and conservation, even in areas of extreme water scarcity. In many areas, the water sector can be the largest energy user when taking into account energy needed for pumping, water treatment and conveyance.
In buildings, implementing a range of water conservation measures – from installing high efficiency fixtures to harvesting rainwater or gray water for use in buildings – can help reduce potable water use by 30% or more.
Collected rainwater or gray water can be used to replace potable water use in buildings for applications such as water closets, landscape irrigation, custodial purposes, and for building systems such as cooling tower makeup water. Rainwater collection systems typically consist of cisterns, underground tanks, or ponds. Rainwater can be collected from roofs, plazas or even paved areas, and then filtered by a combination of graded screens and paper filters to prepare it for use within buildings. Graywater consists of wastewater from sinks, showers and washing machines, cooling tower bleed down water, condensation from air conditioning systems, and other building activities that do not involve human waste or food processing.