Global trends in population increase, urbanization, and economic growth are increasing the demand for water. The unpredictability of future conditions, most notably climate change, compels society to choose and fund mitigation measures in advance. Quantification of the distribution of results following both action and inaction techniques is thus necessary as a result. One such tactic would be the beneficial reuse of treated wastewater, a trend that, predictably, is now gaining ground mostly in arid and semi-arid regions of the world.
Water shortages can be lessened by reusing cleaned wastewater. It can take the place of natural freshwater sources as a reasonably reliable source of supply. However, the affordability of this solution may depend on the expenses of the treatment procedure, those related to direct input use, and those potentially impacted by regulatory requirements, quality enhancement concerns, and other factors. Surprisingly, the study of wastewater treatment, which is also a public benefit activity, has traditionally been limited to engineers and the periphery of economic research.
The world’s unrealized potential for wastewater reuse was recently found via a survey. 40 and 30%, respectively, of the 181 nations surveyed between 1995 and 2012 provided incomplete and complete data on wastewater generated, treated, and reused, reported in cubic kilometers per year. This data set implies that 340, 165, and 24 km3 of wastewater are generated, treated, and reused globally each year, albeit this estimate is not exact. In many nations, this considerable potential has not yet been fully realized. According to the degree of natural recharge envisaged and using Israel as a case study, assessed the contribution of treated wastewater reuse to the regional water economy at between 330 and 460 thousand USD per 1 million m3 of reused water annually over a long period of time. The figures cited above provide an estimate of roughly 46 to 64 billion USD in worldwide economic welfare that could be realized annually through the reuse of existing treated wastewater, though these estimates are obviously dependent on local conditions, which most likely vary considerably on a global scale. The anticipated worth of future harm to water resources brought on by a 1 C increase in the global mean temperature is equivalent to between 54 and 76 percent of an alternative measure. Therefore, it is impossible to overlook the possibility of returning these advantages to the economy.
Several warnings must be made as more nations come to understand the importance of wastewater in managing their water resources and invest both public and private expenditures in wastewater infrastructure.
Greater environmental and water resource demand is brought on by an increase in the number of rich metropolitan residents. On the one hand, this entails a rise in the need for water and a bigger volume of sewage production that calls for treatment to lower health risks and harm to the environment. On the other hand, stabilized and high-quality water supplies can be obtained from treated municipal effluent. However, as wastewater collection, treatment, and disposal are all resource- and energy-intensive procedures, they have an impact on the advantages of having a second, consistent source of water. As a result, the need for treatment has become a costly social problem that calls for sound public policy.
Because of this conundrum, which is related to trade-offs in public budgets, the majority of underdeveloped nations still do not treat wastewater, while industrialized nations deal with issues ranging in severity with the economic viability of treatment investments and the disposal of substandard wastewater. Future climate uncertainty only makes this predicament worse. Climate change effects could have opposing effects on the social costs of wastewater treatment. A higher frequency of extreme climatic events, such as floods, and cold or hot weather, might impair the efficiency of the treatment process, making it much more Water 2020, 12, 3272 20 of 31 expensive and less effective. This is true even though recurrent droughts, dry and warm conditions encourage the potential use of treated wastewater as a substitute to natural freshwater for beneficial uses. Wastewater-related activities typically exhibit some degree of centrality due to their placement within the public good domain, making them more vulnerable to governmental interventions. However, the possible effects of climate change must be measured in order to conduct the social cost-benefit analysis. The current work thus makes a first step toward a better understanding of how climate change will affect actual operating costs of wastewater treatment and, eventually, how societies will be able to deal with hazards associated with worsening water scarcity.