Effect of the tap water supply system on China's economy and energy consumption, and its emissions' impact

Water supply systems have led to the related effects on goals of nation energy consumption, environmental protection and economic development due to their energy use, pollutants discharge and economic cost. This work put forward a set of indicator system and the related methods, based on energy, current, mass and emergy, to describe the complicated interactions between water supply systems, economic development, energy consumption and environmental impact. As a case, the proposed indicators and methods were used to explore the effects of China's tap water supply system (TWSS) on national economy, energy and environment from 2000 to 2013, so as to discover some underlying obstacles hindering the sustainable development of China's TWSS. The study results show that (1) per capita water use declines by 28.11% from 102.17 t/person in 2000 to 73.45 t/person in 2013; (2) the contribution of China's TWSS to national economy and energy decreases by annual decline rates of 5.37% and 3.66% respectively; (3) the total pollution discharge from this system ascends by an annual growth rate of 1.06%, of which 97.44% comes from sludge discharge in terms of mass; therein, the contribution of COD discharge from this system to national COD discharge rises by an annual growth rate of 2.57% while the contribution of sludge discharge from this system to national sludge discharge falls by an annual decrease rate of 9.26%; generally the environmental impact intensity of this system ascends by an annual growth rate of 0.17%; (4) the annual average leakage rate of 16.49% leads to a lot of water waste. Therefore, China's government will still face the two serious challenges derived from the rising water demand and the increasing energy consumption from tap water supply with development of its society and economy. After discussing the related issues, this work gives the corresponding policy suggestions.