Water supply and sanitation infrastructure and services are become increasingly susceptible to the impacts of climate change. Climate change is manifesting itself in the form of more frequent and/or more severe extreme events such as floods and droughts, shifts in rainfall patterns, and local temperatures. Severe and frequent droughts and floods have the potential to adversely affect availability and quality of surface and ground water, which can in turn threaten water security. Since water supply and sanitation services are typically delivered via networks infrastructure with large geographic spreads, this makes them quite vulnerable to disruption from natural hazards. Water and wastewater systems have a two-way relationship with climate change. While the water-energy nexus has been well-known and well-researched for several decades, the water-energy-carbon nexus is receiving greater focus now. In simple terms, increasing demand for water lead to increasing energy use (in water and wastewater systems), which in turn leads to higher carbon emissions that drive climate change, whose effects negatively impact availability of both water and energy. It is therefore quite essential to move to a low-carbon pathway to break this nexus.
Both the water and wastewater sector offer ample opportunities for contributing to climate mitigation by way of reducing greenhouse gas emissions and their effects. This is possible by reducing energy consumption by improving energy efficiency, improving water-use efficiency, promoting use of renewable energy, recovering energy from wastewater, reducing direct emissions from wastewater management, and offsetting carbon emissions by re-using wastewater by-products.