Cambodia & Environment: The race to clean up rivers in the face of an unstoppable flow of sewage

Cambodia, a country criss-crossed by iconic rivers and lakes such as the Mekong and Tonlé Sap, is engaged in a difficult struggle to restore the purity of its waters. Despite ambitious efforts by the government and local stakeholders, river pollution persists, fuelled by massive and often uncontrolled discharge of wastewater.

In urban areas, domestic and industrial wastewater reaches enormous volumes

This contrasting reality highlights a crucial battle for public health, biodiversity preservation and sustainable development in the kingdom.

An alarming situation despite progress

In recent years, Phnom Penh, the capital, and other Cambodian cities have seen the emergence of their first wastewater treatment facilities. A treatment plant was recently inaugurated in the capital, marking a long-awaited turning point towards better urban liquid waste management. However, the majority of wastewater continues to be discharged without adequate treatment into major waterways, exacerbating an already worrying pollution problem.

In urban areas, the volume of domestic and industrial wastewater is enormous. In Phnom Penh, more than 8,000 m³ of greywater and more than 200 tonnes of faecal matter are discharged every day. The city, with its often obsolete and inadequate sanitation network, struggles to contain the damage, especially during the rainy season when recurrent flooding further disperses pollutants.

Industrial pollution and government vigilance

Factories and businesses are identified as major sources of pollution. In 2024 and 2025, more than 30 establishments, including food processing plants such as Cangxinlong Food in Pailin, were penalised for discharging untreated wastewater into rivers and drinking water sources, causing significant damage to the environment and the health of local populations.

In response to this crisis, the Cambodian Prime Minister ordered the immediate closure of polluting companies and more inspections to make sure the new wastewater treatment law passed at the end of 2024 is strictly followed.

This law establishes a strengthened regulatory framework for the construction, operation, maintenance and management of treatment infrastructure, with heavy penalties for non-compliance.

Local initiatives: the key role of NGOs and communities

One of the most promising examples of the fight against river pollution is the clean-up mission undertaken by the Cambodian NGO River Ocean Cleanup (ROC) in cooperation with Leader Energy Holdings. Since its official launch in March 2024, this initiative has removed nearly 1,700 tonnes of waste from rivers in Phnom Penh and Kandal province. This privately funded project illustrates the power of local mobilisation combined with the support of responsible businesses.

However, ROC stresses that cleaning alone is not enough. These actions must be accompanied by effective waste management at source, public awareness campaigns and strict enforcement of environmental laws to prevent pollution from recurring.

The critical case of Tonlé Sap Lake

Tonlé Sap Lake, the country's ecological and food lung, is facing accelerated deterioration in its water quality. Wastewater from floating villages, where thousands of families live on stilts, flows directly into the lake without adequate sanitation infrastructure. The consequences are dramatic: dangerous bacterial contamination, recurrent intestinal diseases in children, and declining fish catches, jeopardising food security and the livelihoods of local communities.

Studies show that millions of litres of untreated wastewater flow into the lake every day, exacerbating eutrophication and the depletion of aquatic biodiversity, which is essential for the region's environmental and economic balance.

Towards sustainable solutions

Against this backdrop, Cambodia has set itself ambitious goals. The government plans to increase wastewater treatment capacity in secondary cities several times over by 2035, with a target of 45% of urban water treated. This will involve building new plants, upgrading networks and strengthening the administrative and financial capacity of local authorities to manage these facilities.

However, the success of these projects will depend on the introduction of an appropriate tariff system to ensure the financial sustainability of services, as well as effective coordination between ministries, local authorities and international partners.

A public health and environmental justice issue

Water pollution poses major health risks for the Cambodian population.

In 2015, more than 15,000 deaths were attributed to pollution-related diseases, a significant proportion of which were linked to contaminated drinking water. Children in polluted areas are particularly vulnerable, with frequent cases of diarrhoeal diseases, a major cause of infant mortality.

Beyond health, pollution affects equitable access to an essential resource, further widening inequalities between developed urban areas and rural or peripheral areas, which are often left without adequate services.

The increase in clean-up efforts and the strengthening of regulatory frameworks are positive signs. However, without ongoing commitment, massive investment in infrastructure, training for local authorities and community education, water pollution will continue to threaten the country's environment, health and economy.