Groundwater affects the lives of everyone. Preserving and protecting it is vital to Asia’s cities and the people who live there.
Groundwater plays an essential role in the development of cities in Asia and the Pacific. It not only helps meet domestic, commercial and industrial water needs, it also accounts for about one third of Asia’s drinking water supply. In some cities, such as Ho Chi Minh City and Lahore, this figure is much higher.
Many municipal water service providers in the region are diversifying their water sources, especially expanding surface water supply where available, to build water security and reduce dependence on groundwater. Compared with alternatives such as desalination and water reuse, groundwater still offers a readily available, and cost-effective municipal water supply option. Groundwater aquifers are also an important “reserve resource” that can be tapped during prolonged droughts when surface water is scarce.
However, rapid groundwater depletion continues in the face of growing water demand. In Asia, more than half of the 4 billion residents of developing countries lived in urban areas in 2019. Cities can expect an additional 1 billion residents by 2050. This will contribute to growing demand for water. Combined with climate change impacts such as more frequent and extreme water-related events including drought, this will pose a challenge to urban water security.
Cities such as Beijing, Ha Noi, and Jakarta have experienced land subsidence, due to over-pumping of groundwater. In coastal cities, over-extraction has resulted in saltwater intrusion in groundwater aquifers.
Inadequate urban water supply disproportionally impacts poor households in the region who tend to use highly contaminated shallow wells that pose significant health risks, where affordable piped supply in unavailable. For example, in Jakarta, less than half of the population is connected to piped water supply, forcing millions of people to rely on illegal wells.
The lack of adequate sanitation in Asia and the Pacific’s cities has contributed to the deterioration of groundwater quality. Centralized wastewater collection and treatment is limited. Most of the population relies on onsite sanitation systems, mostly septic tanks that are often poorly constructed and maintained, resulting in pollution of groundwater, particularly shallow aquifers.
Though groundwater is not visible to most people, it affects the lives of everyone.
So how can cities in Asia and the Pacific better manage and protect groundwater in the face of growing urbanization and climate change risks?
- Improve and expand access to piped water supply services and sanitation. As experience in Bangkok and Osaka has shown, making available adequate alternative sources of water can reduce the incentives for households and industries to tap groundwater supplies to meet their water needs. Expanding access to improved wastewater treatment systems will reduce groundwater pollution.
- Regulate and charge for groundwater. A recent ADB survey found that 79% of the Asian countries surveyed have no policy instruments to allocate or monitor groundwater. Introduction and enforcement of a groundwater licensing system can help to better manage groundwater abstraction. Introducing a system of groundwater charges can reduce incentives for self-supply using private boreholes by properly pricing groundwater, and encourage households and businesses to connect to municipal water supply systems, where this provides a viable alternative.
- Promote water conservation to manage growing demand for water. This includes demand management measures such as water pricing to reduce water wastage. Similarly, households and industries should be encouraged to invest in water-saving technologies. There is increasing interest in the potential for decentralized water reuse systems, which collect and treat water for non-potable reuse within buildings, to reduce water usage. For example, San Francisco has become the first city in the United States to require newly constructed buildings over 250,000 square feet to install onsite water reuse systems.
- Improve groundwater measurement and monitoring. Aquifer mapping and continuous monitoring of groundwater levels and quality is needed to move extraction to more sustainable levels. Technologies such as satellite data are making it easier and cheaper to effectively monitor groundwater.
- Implement managed aquifer recharge where appropriate to intentionally recharge aquifers and maintain groundwater levels. Cities around the world are also using managed aquifer recharge to create “water banks” that can be accessed as backup supply during drought.
- Engage with the public. Enforcement of groundwater regulations is challenging, particularly cracking down on illegal private groundwater wells. Engaging the public and raising awareness about the risks of uncontrolled groundwater extraction, to make sustainable groundwater management everyone’s business, can help to tackle this problem.
This year’s World Water Day theme “Groundwater: Making the invisible visible” reflects an understanding that though groundwater is not visible to most people, it affects the lives of everyone. Preserving and protecting it is vital to Asia’s cities and the people who live there.