By Rath Lyfong
Cambodia’s wastewater system is under growing strain from rapid urbanization, combined sewer systems and limited treatment capacity. These challenges complicate sanitation management, damage the environment and threaten public health. Inadequate wastewater management can also impede economic growth by degrading water resources, undermining tourism and increasing health care costs.
Limited Wastewater Treatment Capacity
A study by the Asian Development Bank (ADB) found that Phnom Penh has limited wastewater treatment capacity, with much of the city’s wastewater discharged into rivers and wetlands without adequate treatment. This contributes to pollution in the Bassac and Mekong river systems and can compromise water quality in communities downstream.
Wastewater treatment infrastructure has not kept pace with Cambodia’s population growth and urban expansion. As more wastewater is generated, treatment capacity remains limited.
According to the ADB, only about 9 percent of Cambodia’s wastewater receives treatment before being discharged, one of the lowest rates in Southeast Asia. Limited investment in treatment facilities and technology is a major contributor to wastewater pollution, highlighting the scale of the country’s sanitation challenge.
Without adequate treatment facilities, harmful substances, bacteria and chemicals can remain in wastewater, contaminating the environment and posing risks to human health. Exposure can contribute to waterborne diseases, particularly among children and poor communities.
Pollution From Untreated Sewage
Untreated sewage pollution occurs when wastewater from homes, industries and other activities enters rivers, lakes or wetlands without proper treatment. The World Bank reports that Cambodia’s sanitation infrastructure has not kept pace with rapid urbanization, allowing untreated wastewater to enter rivers and wetlands.
In Phnom Penh, this has raised concerns about water pollution and environmental degradation near wastewater discharge areas. Sewage can carry organic waste, hazardous substances and harmful microorganisms into waterways.
Industrial and Illegal Discharges
Industrial and illegal wastewater discharges also contribute to pollution. Some industrial facilities release untreated wastewater into rivers, canals and drainage systems, where it can mix with sewage. If industrial wastewater is not treated properly, it can introduce
harmful chemicals and substances into the sewage system, increasing water contamination.
Polluted water can produce unpleasant odors and make waterways unsuitable for some uses. Wastewater pollution also threatens human and environmental health. The World Health Organization warns that inadequate sanitation can expose people to harmful substances and spread disease.
Polluted wastewater also harms aquatic ecosystems, biodiversity and fish populations on which some communities depend for food and income. These effects undermine sustainable development.
Advanced Wastewater Treatment in Phnom Penh
Tertiary wastewater treatment is an advanced stage of treatment that removes remaining impurities and contaminants after secondary treatment, improving water quality before discharge or reuse. The process uses advanced methods such as filtration and biological processes to reduce nutrients, pathogens and other contaminants. Technologies used in this process may include filtration and disinfection methods such as chlorination and ultraviolet light.
The Choeung Ek Wastewater Treatment Plant
In Phnom Penh, the Choeung Ek Wastewater Treatment Plant began operations in 2023. With support from the Japan International Cooperation Agency, the plant is designed to treat 5,000 cubic meters of wastewater per day using pre-treated trickling-filter technology.
The facility is intended to reduce water pollution, improve the quality of wastewater discharged into receiving water bodies, protect public health and the environment, and support sustainable urban development in Phnom Penh.
Reducing Water Pollution
Cambodia needs to invest in infrastructure, modern technologies and public participation to reduce wastewater pollution. One measure is to invest in wastewater treatment plants, particularly in towns such as Phnom Penh, to treat sewage before it is discharged into rivers or lakes.
Cambodia can invest in environmentally friendly technologies by allocating more public funding, working with international organizations, and encouraging private companies to develop affordable wastewater treatment systems such as biofilters and reed-bed filtration systems. It is also essential to improve sewage infrastructure by developing drainage systems, separating sewage from rainwater, and expanding sewer networks to prevent wastewater from flowing into natural water bodies such as the Mekong River.
Strengthening Wastewater Management
The government should expand the number of households connected to sewer networks so wastewater can be directed to treatment plants instead of being released into rivers, canals and drainage systems. Existing infrastructure also needs regular maintenance to prevent blocked sewer lines, leaks, overflows and damage to treatment facilities.
Authorities should conduct regular inspections of factories and businesses and penalize companies that violate regulations by discharging untreated wastewater into rivers. Consistent enforcement would encourage compliance and help reduce industrial contamination in rivers and other water bodies.
Public awareness can be strengthened through school education, television and social media campaigns, community cleanup programs, and workshops organized by local authorities and environmental organizations. The government can also increase investment by allocating a larger portion of the national budget to water and sanitation projects, seeking financial support from international development partners and partnering with private companies to expand clean water infrastructure.
Rath Lyfong is an undergraduate student pursuing a bachelor’s degree in international relations at the Institute for International Studies and Public Policy. Her research interests include environmental sustainability in Cambodia, wastewater management and social development.
