Modeling and reliability assessment for rainwater harvesting system in a tropical region
T. Ahmad Mohammad1*, M. Johari Megat Mohd. Noor2
A rainwater harvesting (RWH) system was installed in UPM for reliability assessment.
The RWH model was assessed using the real data on roof, roof material and rainwater intensity.
Reliability was evaluated then using the real data collected from the installed system.
The harvested rainwater was used for toilet flushing in UPM.
The reliability of RWH system was found to be ranged between 26.6 and 100%.
Rainwater harvesting is a technique of capturing, storing and using the rainwater for meeting part of domestic water demand in both urban and rural areas. Reliability of a rainwater harvesting system is used to compare the collected volume of rainwater with the consumed water volume either for potable or non-potable uses. Typically, the rainwater harvesting system is composed of the catchment (roof), gutter, rainwater pipe, and storage tank. In the present study, a rainwater harvesting system is installed at the Faculty of Engineering, University Putra Malaysia, Malaysia. The system is tested using the data for 24 different rain events. The collected data includes rain depth and rainwater volume. Depending on rainwater depth and duration, it is found that the rainwater volume was ranged between 0.027 and 4.03 m³. The actual data is used to produce an empirical model for predicting the collected rainwater volume. Calibration and validation processes are conducted to the proposed model and T-test shows that the model prediction is within 95% level of confidence. Also, the water consumption for toilet flushing is monitored using water meter. Depending on the daily water demand and recorded rainwater depth, the reliability of the installed rainwater harvesting system when used for toilet flushing was computed and found to be ranged between 26.61 and 100%.