Monitoring on The Quality and Quantity of DIY Rainwater Harvesting System

Abstract

Abstract.Rainwater harvesting is an alternative sources of water supply and can be used for potable and non-potable uses. It could helps to store treated rainwater for more beneficial use and also for flood mitigation. Sustainable approach for flooding problem reduction in urban areas is by slowing down the rate of surface runoff flows at source by providing more storage area/tank. In order to understand the performance of a rainwater harvesting system (RWH), a preliminary monitoring on a 'do it yourself' (DIY) RWH model with additional first-flush strategy for water quality treatment was done. The main concept behind first flush diversion is to prevent initial polluted rainwater from entering the storage tank. Based on seven rainfall events observed in Parit Raja, both quality and quantity of the rainfalls were analysed. For rainwater quality, the samples from first flush diverter and storage tank were taken to understand their performance based on pH, dissolved oxygen (DO), turbidity, total dissolved solid (TDS), total suspended solid (TSS), chemical oxygen demand (COD) and biochemical oxygen demand (BOD) parameters. While for rainwater quantity, hydrograph analysis were done based on the performance of total rainfall and runoff, peak flow of rainfall and runoff; and delayed time parameters. Based on Interim National Water Quality Standard (INWQS) and National Drinking Water Quality Standard (NDWQS), first flush diverter apparently helps on water quality improvement in storage tanks when pH, DO, TDS, TSS and turbidity were classified as Class I (INWQS) and is allowable for drinking; but BOD and COD parameters were classified as Class III (INWQS). Hence, it has potential to be used as potable usage but will need extensive treatment to reduce its poor microbial quality. Based on the maximum observed rainfall event which had total volume of 3195.5 liter, had peakflow reduction from 0.00071 m 3 /s to 0.00034 m 3 /s and delayed runoff between 5 and 10 minutes after rainfall started. It concludes that the performance of water retention could be due to total rainfall and the tank capacity. Therefore, RWH has a potential to be used as potable use and at the same time it also has a potential to reduce local urban flooding.

The Outlook of Rural Water Supply in Developing Country: Review on Sabah, Malaysia

“…October 2016 November 2016 Quality of rainwater is influenced by several factors such as the locality and neighbour ing activities, collection system and storage material, rainfall time span, and interval of wet and dry climate (Che- Ani, Shaari, et al, 2009;Kasmin, Bakar, et al, 2016;Yaziz, Gunting, et al, 1989;Despins, Farahbakhsh, et al, 2009;Shaheed, Wan Mohtar, et al, 2017). In general, urban areas with more industrial activities will have more suspended debris in the atmosphere which will be carried during rainfall (Man, 2015).…”

“…Utilization of a galvanized metal roof may cause zinc leaching (Lee, Yang, et al, 2010;Yaziz, Gunting, et al, 1989;Nicholson, Clark, et al, 2009), while old and corroded roof is the main contributor to heavy metal contamina tio n (Sánchez, Cohim, et al, 2015). Other than heavy metal, microbial contamination (Kasmin, Bakar, et al, 2016) from bacteria and pathogen are also significant mainly due to animal droppings or decomposing dead animals left on harvesting surface (Ahmed, Gardner, et al, 2011). Based on the annual precipitation level around Sabah, employment of rainwater harvesting and collection for freshwater source is highly potential.…”

A Review of Roof and Pond Rainwater Harvesting Systems for Water Security: The Design, Performance and Way Forward

“…Other factors that need to be considered are rainfall events and the size of storage tanks. The usage of a smaller storage system in an RHS as compared to a PHS gives the advantages of allowing the collection of all rainfall events and the pollutant being flushed away through the first flush device [94]. However, the quality of harvested rainwater will deteriorate through extreme events that occur from the worst climate change.…”

A Review of Roof and Pond Rainwater Harvesting System: The Design, Performance and Way Forward

“…In RHS application, the harvested rainwater showed better water quality through the smaller and more frequent rainfall events [72]. The usage of smaller storage system in RHS as compared to PHS gives the advantages to allow the collection of all rainfall events and flushed away the pollutant through the first flush device [73]. However, the quality of harvested rainwater will deteriorate through the extreme events that occurred from the worst climate change.…”