Water saving potential and economic viability assessment of rainwater harvesting system for four different climatic regions in China

Abstract

Rainwater is one of the most promising alternative water sources. However, the financial outcomes of the rainwater harvesting systems are not always assured due to the economic performance of RWH system varies greatly under different climatic conditions.This paper investigates reliability,water saving and benefit cost ratio of RWH system with different storage tanks and under three distinct climatic conditions (i.e.,wet, average and dry year) at four cities in China. It is found that for a standard building (1,600 m2 roof having 560 people), the rainwater supply reliability varies significantly (3.85–20.55%) across four cities. It is found that Guangzhou (South China) is always achieving the highest reliability, greatest annual water saving and highest benefit cost ratio under three distinct climate conditions. In the contrary, Beijing (North-China) is mostly ranked as having the lowest one. These findings are well in line with the historical annual precipitation in these regions. Also, it is found that across these four regions, it is not possible for a RWH system to achieve benefit cost ratio higher than 1.0. These findings indicate that the RWH systems in most regions of China is currently economically unfeasible without government subsidies.

Development of an analytical solution for optimum design of RWH systems—A case study in Guangzhou

“…For example, for an 8-story office building with a roof area of 1600 m 2 and 500 occupants in the Guangzhou area (with an average annual precipitation of 1790 mm), the AWS reach 2000 m 3 , accounting for approximately 33% of the total water consumption of the building throughout the year. When the storage volume is optimized, the unit construction cost of the RWH system is 2.62 CNY/m 2 and the dynamic payback period is 12.1 years (Shiguang & Yu, 2021).…”

Comprehensive evaluation of rainwater utilization in China: potential, feasibility and strategy

“…The specific formula of the daily rainfall–water balance model is shown in eqn (2) and (3): Q t = P t + V t −1 − D where P t = ρ × H × A − FFLwhen Q t < 0, V t = 0;when Q t > C , V t = C ;where Q t is the cumulative water stored in the rainwater tank (m 3 ) after the end of the t th day, P t is the harvested rainwater (m 3 ) on the t th day, V t −1 is the storage in the tank (m 3 ) at the end of the ( t − 1)th day, D is the daily rainwater demand (m 3 ), ρ is the runoff co-efficient (0.9), H is the daily rainfall (mm), A is the roof area (m 2 ), and FFL (first flash loss) is considered to be 150 L. If Q t −1 > FFL, then FFL for day ‘ t ’ is computed to be 10% only (15 L). 15 C is the capacity of the rainwater tank (m 3 ).…”

“…This result is similar to a recent study by Chen and Zhang who found that climate change variabilities for expected water savings are more significant in Guangzhou and Harbin than those in Wuhan and Beijing. 15 To sum up, when adopting RHSs, each region can comprehensively consider local water consumption, water saving benefits and climate change impact to formulate an appropriate rainwater utilization strategy.…”

“…14 Chen and Zhang examined the performance of a RHS for an official building in four major cities in China, and according to their economic viability assessment, the RHSs in most regions of China are currently economically unfeasible without government subsidies. 15 Feng et al evaluated the utilizable potential of rainwater in Zhengzhou, China and found that the collection volume of rainwater resources is 0. 86 × l0 6 m 3 per year and the resources can bring a benefit of about 4.…”

Socioeconomic potential for rainwater harvesting systems in southern Brazilian municipalities

“…Socioeconomic criteria should incorporate issues such as distance from settlements, family size, education level and water price, which can improve the RWH effectiveness (Pavolová et al 2019) while at the same time allowing for the planning of future structures. Furthermore, other factors such as funding and government subsidies (Fernandes et al 2020;Shiguang & Yu 2021) can make the RWH economically viable. Nevertheless, the establishment of good socioeconomic indicators associated with RWH system performance is much more difficult for socioeconomic conditions than for technical conditions (Adham et al 2018).…”