Rainwater Harvesting System Analysis

Increasing population growth has led to an increase in demand for clean water. On the other side, the provision of clean water is a common problem in terms of both quantity and quality. Consequently, water shortages often occur, especially in major cities, including in Indonesia. Following that, another solution in which provision of alternative water resource that is cheap and easily accessible, is important. One source of clean water that is often forgotten is rainwater. The volume of unused rainwater can be harnessed and used as a substitute for clean water. Rainwater can be captured and stored in a simple system which is commonly referred to as Rainwater Harvesting (RWH) system.

RWH system is a simple system that uses roof as a catchment

Generally, to analyze the RWH system performance, long rainfall data duration is used in calculations. Unfortunately, the availability of long rainfall data duration is sometimes difficult to obtain. Therefore, the use of rainfall data with short duration should not be discarded.

The 34 years daily rainfall data duration were used to analyze the RWH system performance for household in Brazil [5]. The use of 20 years of rainfall data are conducted by Fewkes in England [6], and Domeneh and Sauri in Spain [7]. Rainfall data below 10 years was also used to analyze the performance of RWH systems in school buildings in Taiwan [8]. Even a 3 years rainfall data duration used to evaluate the performance of RWH systems for domestic water use in Sweden [9].

Many rainfall data variations used by several researchers, both in terms of data duration and time period. Sets of a short duration of rainfall data can be uses to assess the RWH system performance and the results are similar to those with the longer duration [10]. However, there are still few studies that construe the effect of appropriate rainfall data duration and time period to be able to predict the proper RWH system performance. Therefore, the main objective of this study is to investigate the effect of the difference between the rainfall data duration and time period to evaluate the RWH system performance. This study examined the possibility of

The RWH system performance for each simulation was then compared to identify the influence of the rainfall data duration and time period.

3. RESULTS AND ANALYSIS

3.1. System performance based on rainfall data duration

In order to determine the adequate rainfall data duration, the RWH system performance (VR) obtained from the long and short duration were calculated and compared. The rainfall data duration was considered adequate if the differences between the long and short duration do not exceed 5%. The influence of rainfall data duration was performed for dry year, wet year, average year, 2, 3, 5, and 15 years daily rainfall data. This was carried out considering rainwater demand for 1 and 4 persons nonpotable water use. Each simulation was conducted for 0.5, 1, 2, and 5 m3 tank capacities. The RWH system performance (VR) obtained from 15 years data duration were used as a