1.0 Introduction
1.1 Background of Study
Historically, the materials used for roofing have undergone significant transformations, from thatched roofs and mud to modern roofing sheets made of galvanized steel, aluminum, and plastic. The introduction of metal roofing sheets in the 20th century revolutionized rainwater harvesting by providing more durable and efficient collection surfaces (Abah & Ibrahim, 2017). However, as the use of metal and synthetic roofing materials became widespread, concerns emerged regarding the quality of water runoff, especially in terms of contamination and its suitability for human consumption.
Early studies on the effects of roofing materials on harvested rainwater focused primarily on the general collection efficiency and the amount of water that could be harvested from different roof surfaces (Yong, 2001). Over time, research began to shift towards the influence of roofing materials on water quality. This shift occurred as public health concerns grew, with studies revealing that certain roofing materials, particularly metal roofs, could leach hazardous substances such as zinc, lead, and other chemicals into the collected rainwater (Simoneit et al., 2017).
In recent decades, scholars have increasingly emphasized the need for more comprehensive studies on the quality of water harvested from various roofing materials, considering factors such as turbidity, pH, total dissolved solids (TDS), and microbial contamination (Zhu et al., 2014). The increasing demand for water in urban and rural areas has prompted the exploration of alternative sources of water supply, one of which is rainwater harvesting (Kumari et al., 2018). This practice involves the collection and storage of rainwater, typically from rooftops, for use in various domestic and agricultural activities. While rainwater harvesting is a sustainable solution to water scarcity, the quality of harvested water is influenced by several factors, including the type of roofing materials used in the collection system (Umar et al., 2020). Roofing sheets, commonly made from materials such as galvanized steel, aluminum, and plastic, are an essential component of rainwater harvesting systems as they direct rainwater into gutters for collection. However, the material properties of these roofing sheets, such as surface texture, and chemical composition, can significantly affect the quality of the water runoff.
According to UNEP (2015), the effects of roofing sheets on harvested water runoff play a critical role in understanding the quality and quantity of rainwater harvesting systems. Rainwater harvesting is the process of collecting and storing rainwater from rooftops, which can serve as a reliable source of water for domestic, agricultural, and industrial purposes (UNEP, 2015). The materials used in roofing, such as roofing sheets, can significantly influence the characteristics of water runoff, including contamination levels, water quality, and the volume of collected rainwater.
Previous studies have shown that certain roofing materials may introduce contaminants into the collected rainwater, which can pose risks to human health if not properly managed (Okoye et al., 2017). For instance, metal roofing sheets may leach substances like zinc or other metals into the runoff, altering the chemical composition of the water (Alhassan et al., 2015). Similarly, roofing materials with rough surfaces may cause water to pick up more dirt and debris, leading to increased turbidity in the harvested water (Akinbile, 2012). Therefore, this study seeks to fill this gap by investigating the relationship between roofing materials and the quality of harvested water, focusing on physical and chemical parameters such as turbidity, pH, total dissolved solids (TDS), and the presence of metals and other contaminants.
1.2 Statement of Problems
Investigation revealed that the increasing reliance on rainwater harvesting as a sustainable water source in many urban and rural areas has raised concerns about the quality of water collected from rooftops. Roofing sheets, often made from materials such as galvanized steel, aluminum, or plastic, are integral to this system. However, these materials have not been sufficiently studied for their impact on the water runoff quality, leading to potential health risks if not properly assessed. As the global demand for alternative water sources grows, the need to understand the specific effects of roofing sheets on the runoff quality of harvested rainwater becomes more pressing.
Research has shown that different roofing materials affect the composition of the water runoff, with some materials introducing contaminants such as metal residues and other particles that compromise water quality (Akinbile, 2012). For instance, metal roofing sheets are known to leach zinc and other potentially harmful metals into the water, while rougher surfaces may trap more debris, increasing the turbidity of the runoff (Alhassan et al., 2015).
Furthermore, without clear guidelines or studies on which roofing materials are most suitable for ensuring safe and clean rainwater harvesting, there is a risk of people unknowingly compromising the quality of their water supply, which could lead to health issues, especially in communities where treated water is scarce. It is against the backdrop that this study seeks to determine how they influence the physical and chemical characteristics of collected water.
1.3 Aim and Objectives of Study
The aim of this study is to evaluate the effects of different types of roofing sheets on the quality of harvested rainwater runoff. The specific objectives of the study are:
- To analyze the pH levels of rainwater runoff collected from various roofing sheets and evaluate its suitability for domestic use.
- To investigate the presence of harmful metals in the harvested water depending on the type of roofing material used.
- To compare the total dissolved solids (TDS) in rainwater runoff from different roofing materials.
- To assess the impact of different roofing materials on the turbidity of harvested rainwater.
- To provide recommendations on the most suitable roofing materials for rainwater harvesting based on their effects on water quality, ensuring safe consumption and usage.
1.4 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- How does the type of roofing material affect the turbidity of harvested rainwater runoff?
- What are the pH levels of rainwater runoff collected from different roofing sheets, and how suitable are they for domestic use?
- To what extent do different roofing materials contribute to the presence of harmful metals (such as zinc, lead, or other contaminants) in the harvested water?
- How do roofing materials influence the concentration of total dissolved solids (TDS) in rainwater runoff?
- What is the overall water quality of harvested rainwater from various roofing sheets in terms of microbial contamination and chemical residues?
- Which roofing materials are most suitable for rainwater harvesting based on their impact on water quality and safety for domestic and other uses?
1.5 Significance of Study
The outcome of this research study will contribute to the broader field of environmental sustainability by offering practical recommendations for improving water quality in regions facing water scarcity. This research will also help minimize the risks associated with contaminated rainwater, promoting a safer and more sustainable approach to water collection and use.
Furthermore, the findings will be significant for policymakers, engineers, and homeowners seeking to optimize rainwater harvesting systems. It will inform the selection of appropriate roofing materials that will ensure cleaner and safer water runoff, ultimately promoting public health
Lastly, the research study will provide guidelines for communities that depend on rainwater harvesting, enabling them to make informed decisions about the materials they use for collecting water.
1.6 Scope of Study
This study will focus on assessing the effects of different roofing sheets on the quality of harvested rainwater runoff in Sokoto State, Nigeria. The study will cover various types of roofing materials commonly used in the region, including galvanized steel, aluminum, and plastic roofing sheets. The research will assess key water quality parameters such as turbidity, pH, total dissolved solids (TDS), and the presence of harmful metals like zinc and lead in the harvested runoff.
1.7 Limitations of the Study
A study of this nature is bound to experience certain problems as such the constraints imposed on the research include:
- Time: A study of this nature needs relatively long time during which information for accurate or at least near accurate inference could be drawn. The period of the study was short, time posed as constraints to the research.
- Cost: The research would have extended the survey to other area at the empirical level, but limitation as included cost of transportation to the source of material and the cost of time setting of the already completed work.
- Lack of Cooperation: Many of the respondents are usually aggressive on issue that border cooperation among the respondents border.
1.8 Definition of Terms
Roofing Sheets:
Roofing sheets refer to the material used to cover the upper structure of a building, providing protection from weather elements. These materials vary in composition, and common types include metal (galvanized steel, aluminum) and synthetic options (such as plastic and fiberglass). Roofing sheets not only serve to protect buildings from rain but can also significantly affect the quality of rainwater runoff, as they may leach contaminants into the collected water (Smith & Jones, 2018).
Harvested Water Runoff:
Harvested water runoff refers to the rainwater that is captured from a building's roof for later use. This runoff is typically collected in tanks or cisterns for purposes such as irrigation, domestic use, or even potable water, depending on the water quality. The quality of harvested water runoff is influenced by the roofing material, weather conditions, and the presence of contaminants (Adekunle et al., 2017).
Turbidity:
Turbidity is a measure of how clear or cloudy the water is, caused by the presence of suspended particles such as dust, sediment, or microorganisms. High turbidity levels in harvested water indicate contamination and can affect its suitability for use. Turbidity is an important parameter when assessing water quality (World Health Organization, 2016).
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