Hope from heavens: Rainwater harvesting can solve coastal water scarcity
Considering the climatic and environmental conditions of Bangladesh's southwestern coast, rainwater harvesting is the most practical and sustainable drinking water solution
"Water for Peace" is the theme of today's World Water Day. On this significant day, imagine a reality where the simple act of satisfying one's thirst becomes a hurdle in everyday life. Access to safe drinking water has long been a challenge on the southwestern coast of Bangladesh, defined by relentless struggle and unwavering determination.
While safe drinking water is easily accessible in many parts of the country, over 2.5 million people in this region face formidable challenges due to excessive salinity in both surface and groundwater.
This isn't solely a historical struggle but a present crisis worsened by various factors, including the impacts of climate change; disasters like cyclones and tidal surges; development, though essential, without proper assessment of the fragility of the local environment; and some other natural and human-made factors.
Proximity to the Bay of Bengal further compounds the challenges faced by the region. In this context, the coastal people fight not only with history but also with contemporary environmental threats that further intensify the pressing demand for a sustainable drinking water solution.
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For generations, communities have been struggling to find year-round accessible, safe drinking water sources, and this issue has been steadily deteriorating due to the rapidly changing climate. As conventional water sources proved insufficient to meet the demands for a continuous supply throughout the year, there was a surge in the need for improved drinking water systems.
Government agencies, along with donors, development agencies, and NGOs, swiftly intervened to introduce diverse water options. Although these initiatives provide clean and safe drinking water, none of them individually ensures year-round access to water. Therefore, people must rely on multiple drinking water sources to fulfil their needs.
Over the past two decades, as the impacts of climate change have become increasingly visible, various improved water sources have been widely used for drinking water supply. These sources include shallow and deep tube wells, rainwater harvesting systems, reverse osmosis (RO) plants, pond sand filters (PSF), restricted or managed ponds, and managed aquifer recharge (MAR).
Yet, within this progress, an ongoing and crucial debate has been revolving around determining the most suitable and sustainable water sources, considering the social, environmental, and economic factors of the communities along the southwestern coast. To address this pressing question, multi-criteria decision analysis (MCDA) has emerged as a highly effective tool for identifying the finest water sources.
This method systematically evaluates critical factors such as the accessibility of community members to water sources; the reliability, acceptability, and affordability of water sources for local people; the social and environmental impacts of these sources; the sustainability of operations and maintenance of the sources; the potential for technology transfer to marginalised areas; and the availability of spare parts for them.
The respective authorities seek the opinions of local residents through participatory rapid appraisal (PRA) to determine which water sources are convenient for them. Afterwards, they used MCDA to evaluate the suitability of the water sources by considering the criteria.
Applying MCDA, various entities, including the Government of Bangladesh (GoB), the United Nations Development Programme (UNDP), and WaterAid, unveiled an ingenious solution to address the persistent issue of drinking water scarcity and ensure the long-term sustainability of drinking water in the coastal area.
Among the selection of improved water systems, rainwater harvesting emerged as the prime and most sustainable water source for this area. With the coastal region receiving a considerable annual rainfall of 2900 mm (source: UNDP), of which more than 70% graces the land during the monsoon season, the potential to harness this abundant natural resource is inordinate.
Communities can effectively utilise this natural gift during the monsoon by preserving and efficiently filtering it during the dry season. Additionally, they can tap into other available water sources that become accessible during this season.
Water tanks and pots installed near households ensure easy access for people, especially women and adolescent girls, who are mainly affected by the burden of collecting drinking water from distant places, constituting more than 80% of the total drinking water collectors. This offers them the opportunity to redirect their efforts and time towards other endeavours, thereby paving the way for empowerment and progress.
Affordability is a prime determinant in selecting a suitable water source. A 2000-litre rainwater harvesting system with a pre-and post-filtration system for a household of an average of five members, ensuring water supply for at least six months of the dry period, can cost anywhere between 35,000 and 40,000 takas, which is significantly high.
However, it is vital to recognise that rainwater harvesting is a long-term investment. When compared to the installation cost and maintenance requirements of other drinking water sources, along with the reliability of the water source, rainwater harvesting emerges as a more sustainable option.
Furthermore, it is worth noting that government agencies, NGOs, and donors are currently taking the initiative to install these systems on a cooperative and instalment basis, thereby alleviating the financial burden on the coastal communities themselves. Minor maintenance, such as simple cleaning and basic repairs, incurs minimal costs, making this water option even more attractive.
The use of locally available materials for maintaining and cleaning the water source contributes to the affordability and sustainability of rainwater harvesting systems. Technology transfer becomes convenient and easy when responsible parties such as the government, NGOs, and donors take charge of the installation.
Consequently, hassle-free practices, a relatively low-tech approach, and a low-cost water supply close to homes have made the rainwater harvesting system socially acceptable and widely embraced by the coastal community.
While high-tech alternative drinking water solutions significantly negatively impact the environment and climate, rainwater harvesting systems offer an environmentally friendly drinking water solution to coastal people.
Despite the affordability and simplicity of operating and maintaining rainwater harvesting systems, the quality of harvested water can be compromised due to inadequate knowledge and suboptimal maintenance practices. Therefore, effective operations and maintenance (O&M) are crucial for the sustainability of this water source.
It is evident that the majority of households on the southwestern coast prioritise the cleaning of their rainwater harvesting systems, especially when these systems are located close to their homes. However, people often lack the willingness to maintain community rainwater harvesting systems.
Considering the climatic and environmental conditions of Bangladesh's southwestern coast, rainwater harvesting is widely recognised as the most practical and sustainable drinking water solution for the area.
It directly contributes to achieving Sustainable Development Goals (SDGs), including Goal 6 (Clean Water and Sanitation) and Goal 13 (Climate Action), by providing a sustainable source of clean drinking water and combating climate change impacts.
Therefore, promoting rainwater harvesting initiatives addresses immediate water scarcity issues while advancing broader SDG objectives.
Tasneem Chowdhury Fahim is a lecturer at the Institute of Disaster Management and Vulnerability Studies (IDMVS) at University of Dhaka. Md Mainul Islam is a Water and Sanitation Specialist at UNDP Bangladesh.
