Study on Potential Uses of Rainwater Harvesting in Urban Areas

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STUDY ON POTENTIAL USES OF RAINWATER HARVESTING IN URBAN AREAS

Thamer Ahmed Mohammed, Megat Johari Megat Mohd. Noor, Abdul Halim Ghazali Department of Civil Engineering Faculty of Engineering University Putra Malaysia 43400 UPM Serdang, Selangor, Malaysia e-mail:thamer@eng.upm.edu.my

Abstract Rainwater harvesting is the collection of water volume from raindrops. Rainwater harvesting has been the main source of water supply for potable and non-potable uses in the old days because the water conveyance systems were not used for water distribution during these days and the method used for rainwater harvesting was simple and primary (rainwater was mostly collected from roofs and some was collected directly from the sky). Usage of the collected water volume from rainwater harvesting was direct and without any treatment. Presently, the water supply systems have improved but the demand is increasing due to the population growth, and development. The available water resources are limited and/or seasonal, which made the experts working in the water sector to search for solutions to the water shortage. Many countries around the world are facing water shortages. Optimization of water usage and the conservation of water as a natural resource can help to overcome water shortage. Rainwater can be used for potable and non-potable uses. The potable uses include drinking, bathing, and cooking and washing. Usually, the rainwater used for this purpose must be treated to remove the contaminants. Non-potable uses include flushing toilets, watering garden and washing floor and treatment of rainwater is not required for these purposes. The volume of rainwater collected from rainwater harvesting system varying from place to place and depends on weather. In a tropical country like Malaysia it is easy to collect 2 m3 in a single rain while 10 m3 was collected annually in Zambia, Africa from a roof of almost of the same size. The main advantages of rainwater harvesting systems are conserving water resources and environment, pollution reduction, help to control flooding, and reduction of impact of weather change. In the present study, a rainwater harvesting system was installed in the Faculty of Engineering, University Putra Malaysia, Malaysia and the system composed of the catchment (roof), gutter, pipe, steel tank and the treatment unit. From 20 different rain events, the collected volume of rainwater in the tank ranges between 0.4 m3 and 2 m3. The daily water consumption by student was monitored for one month and compared with the collected rainwater volume. Samples of rainwater was collected from the gutter of the rainwater harvesting system and standard analysis was conducted in the laboratory in order to check the quality of rainwater. The main tests conducted on the rainwater are pH, turbidity, BOD5, dissolved solids, total solids, total coliform, lead,..etc. The rainwater was found to be acidic in nature (pH < 7). Keywords: Rainwater harvesting system, storage, demand, urban areas

Introduction World’s population has been constantly increasing and so has the water demand. However, supplies from water resources are limited and estimated to be 2% from the total available water in nature. The population growth has direct influence on the water supply demand rates. For example, worldwide water demand has increased six folds between 1990 and 1995 while the population was only doubled and the demand of the agricultural sector is almost 70% of the total demand [1]. The rate of the growth in the urban area is about four times that of the rural areas. Based on this fact, the concept of sustainability must be considered in planning and management of the available water resources. With the development and growth of urban populations, the paved and roof area will increase and this situation is ideal for implementing rainwater harvesting techniques. Rainwater harvesting has been the main source of water supply for potable and non-potable uses in...
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