Harvested Rainwater Quality: A Case Study Of Aule In Akure, South Western Nigeria

European Scientific Journal April 2016 edition vol.12, No.11 ISSN: 1857 – 7881 (Print) e - ISSN 1857- 7431 Harvested Rainwater Quality: A Case Study Of Aule In Akure, South Western Nigeria Ochuko Mary Ojo Department of Civil and Environmental Engineering, the Federal University of Technology, Akure, Nigeria doi: 10.19044/esj.2016.v12n11p451 URL:http://dx.doi.org/10.19044/esj.2016.v12n11p451 Abstract The quality of harvested rainwater in Aule area of Akure, South western Nigeria was assessed in this study. Water samples were collected from 25 rain water storage tanks within the study area and a well was used as a control. The water samples were subjected to detailed laboratory analysis and the results obtained was compared with World Health Organization (WHO) standard for drinking water. The turbidity values ranged from 2.7 to 9.1 NTU for the harvested rainwater samples while the well water sample had a turbidity of 2.3 NTU. The conductivity values for the rainwater samples ranged from 101 to 1328 Ωs/cm. The conductivity value was lower in the well water (164 Ωs/cm) than in most of the harvested rain water samples. The pH of the harvested rainwater ranged from 6.1 to 7.4 with 36 % of the water samples having a pH less than the WHO minimum limit of 6.5. The pH of the well water sample was 7.4 and was within the WHO acceptable limits of 6.5 to 8.5. All the sampled rainwaters and well water had bacteria in them. The total bacterial content of the rain water samples ranged from 05 to 28 CFU/100 mL, while that of the well was 05 CFU/100 mL. The total coliform contents of the rainwater samples ranged from 03 to 18 CFU/100 mL, while that of the well was 02 CFU/ 100 mL. Based on the results obtained from this study, it is recommended that harvested rainwater be treated to kill contaminating microorganisms and to reduce the health risks associated with its consumption. Keywords: Akure, harvested rainwater, storage tanks, consumption Introduction Water is identified as one of the most important natural resources because it is viewed as a key to prosperity and wealth (Arbués et al., 2003). Increase in human population has exerted an enormous pressure on the provision of safe drinking water especially in developing countries (Umeh et 451 European Scientific Journal April 2016 edition vol.12, No.11 ISSN: 1857 – 7881 (Print) e - ISSN 1857- 7431 al., 2005). Freshwater quality and availability remain one of the most critical environmental and sustainability issues of the twenty-first century (UNEP, 2002). Unsafe water is a global public health threat, placing persons at risk for a host of diarrheal and other diseases as well as chemical intoxication (Hughes and Koplan, 2005). Unsanitary water particularly has devastating effects on young children in the developing world. Each year, more than 2 million persons, mostly children less than 5 years of age, die of diarrheal disease (Kosek et al., 2003; Parashar et al., 2003). Nearly 90% of diarrhealrelated deaths have been attributed to unsafe or inadequate water supplies and sanitation conditions affecting a large part of the world’s population (WHO, 2004; Hughes and Koplan, 2005). An estimated 1.1 billion persons (one sixth of the world’s population) lack access to clean water and 2.6 billion to adequate sanitation (WHO, 2005; Hughes and Koplan, 2005). The sources of water supply in most parts of developing countries areas include conventional communal sources and self-supply sources. Conformation of potable water with water quality standards is of special interest because of the capacity of water to spread diseases within a large population. Although the standards vary from place to place, the objective anywhere is to reduce the possibility of spreading water-borne disease in addition to being pleasant to drink, which implies that it must be wholesome and palatable in all respects (Edema et al., 2001; Okonko et al., 2008). A collaborative, interdisciplinary effort to ensure global access to safe water, basic sanitation, and improved hygiene is the foundation for ending cycle of poverty and diseases (Hughes and Koplan, 2005). Well water is the main source of water in Akure, Ondo state as surface water is not reachable in most communities. However, well water is not easily accessible in some areas of Akure due to the rocky nature of the soil. The prospects of drilling bore hole for some residents of such areas is a mission that seems impossible to achieve. As a result, they result to rainwater harvesting to meet some of their water needs especially during seasons of high rainfall. . In the past, it was believed that rainwater was pure and could be consumed without pre-treatment. While this may be true in some areas that are relatively unpolluted, rainwater collected in many locations contains impurities. In the last three decades, “acid rain” has affected the quality of the collected water, to the point where it now usually requires treatment. Good quality drinking water should be free from disease-causing organisms and harmful chemical. Common health concerns for rainwater quality in developing countries are related to bacteria, particularly e-coli and to aesthetic properties, such as colour, taste, smell and hardness (Zhu, 2004). The aim of this study is to assess the quality of harvested rainwater in Aule area of Akure. 452 European Scientific Journal April 2016 edition vol.12, No.11 ISSN: 1857 – 7881 (Print) e - ISSN 1857- 7431 Methodology The study was carried out in Aule in Akure. Akure is the capital of Ondo state, which is located in the South-western part of Nigeria. Akure lies on latitude 7o 15ʹ North of the Equator and on longitude 5o 15ʹ east of the Greenwich meridian. Water samples were collected from 25 rain water storage tanks within the study area. A sample was also collected from a well to serve as control. Plate 1 shows a typical rain water harvesting system in the study area. Plate 1: A typical rain water harvesting system in the study area. All the collected samples were taken to the laboratory within two hours of collection and refrigerated at 4°C in the laboratory till the analysis was carried out. Great care was taken to ensure the integrity of the samples. Various physio-chemical and bacteriological analysis were carried out on the water samples as described in APHA (2005). Results and discussion The results revealed that most of the samples had high concentrations of the physico-chemical and bacteriological parameters analyzed; often above the guideline values sourced from the WHO. Temperature The temperature of any water body affects the rate of proliferation of microorganisms (Pelczar et al., 2005). The temperature range of the samples rain water was 25.2 to 28.6 oC while the temperature of the well water sample was 27.8oC. Figure 1 shows the temperature of the sampled waters. Although the temperature fell within WHO permissible limit of 23 to 40 oC, the temperature recorded could be said to be suit (...truncated)