Rainwater Harvesting as an Alternative Sources of Clean Water in Semarang City – Indonesia

City-dwellers in Indonesia are employing rainwater harvesting to combat the flooding and drought made worse by climate change. “Rainwater Harvesting as an Alternative Sources of Clean Water in Semarang City” helps urban Indonesians install rainwater catchment systems in their homes and in shared spaces. The project improves city-dwellers access to clean water while supporting aquifer recharge.

Fast facts:

  • 60 percent of Semarang citizens not connected to water piping

  • City land is subsiding at rates of up to 20 centimeters per year

  • 3,000 Semarang residents benefitted from project

  • City environmental agency to replicate the project

The problem

Semarang is one of Indonesia’s largest cities, with a population of more than 1.5 million. Due in part to its topography, the public water service company is unable to serve all of Semarang’s population – so they rely on wells, mostly shallow ones, since few people own deep wells. But drought and flooding related to climate change are affecting these wells. During the dry season, the shallow wells run dry, and people need to buy water or rely on government aid. During the rainy season, the shallow wells get polluted when floodwater breaches the wells’ walls.

Overdrawing the wells during dry seasons also contributes to subsidence, a situation where ground levels sink due to compaction of the earth as the water is removed. Subsidence represents a serious problem, particularly for densely populated cities, as it can damage structures and create living hazards.


The solution

Semarang residents have been building rainwater harvesting systems in this partnership between the government, local academics, non-governmental organizations (such as ACCCRN), companies, and community members. Systems were installed in five households, as well as at an elementary school.

Since the harvested rainwater is stored in closed tanks, it is kept safe from contamination during floods. Furthermore the use of collected rainwater during the wet season allows wells to recharge, so when the dry season comes, water is available.

Helping the planet

Harvesting rainwater puts less pressure on groundwater resources. Additionally, allowing the aquifer to recharge helps restore ecological balance. Rainwater collection reduces runoff and thus flooding, preventing the environmental damage such flooding may cause.


Helping people

Rainwater harvesting gives city residents a clean, local, and renewable water source. Hygiene and sanitation are improved, particularly for children and teachers at the school. City residents face fewer risks to loss of life and property due to flooding or subsidence. They also save money from not having to purchase water, which especially helps poorer populations.


Spillover effect

The Semarang Environmental Agency has recognized the benefit of rainwater harvesting and replicated the project at 49 locations. These efforts can be used to inform policy-making, particularly if Semarang City incentivizes citizens to install such systems. The project can catalyze a transformational change in behavior, as Semarang residents change previously held views of rainwater as dirty.



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