Water Treatment

Cambodia’s Water Resources

Cambodia has abundant freshwater resources. The Mekong River, Tonle Sap Lake and Tonle Sap river are the main sources of freshwater for the country. The Mekong River flows through Cambodia over 500 km from Laos’s border to the Mekong Delta in South Vietnam, bringing a large volume of water flowing across its territories. The Tonle Sap Lake, the largest freshwater lake in Southeast Asia, takes and releases millions of cubic meters of water from and to the Mekong River. The Tonle Sap Lake occupies approximately 2.2% of the total area of the country. The Tonle Sap River connects the Mekong river to the Tonle Sap Lake.  

The climate features warm to hot temperatures throughout the year and an annual monsoon cycle of alternating wet and dry seasons. The main wet season, the southwest monsoon, occurs between June and October, during which approximately 80% of all rainfall occurs. During the cooler months between November and May, airflows are drier, resulting in cooler and less rainy weather. The average monthly rainfall is around 1,500 millimeters. 

Map of Cambodia  

Water Supply

The water supply authorities in Cambodia have access to various resources (surface water, groundwater and rainwater) to supply households and businesses with drinkable water. Water consumption has increased significantly over the last 15 years, especially in urban areas, and today the development of water supply and wastewater treatment infrastructures are among the priorities of the authorities.  

Water supply in Phnom Penh and Siem Reap is managed by public independent enterprises in charge of providing drinkable water. The Ministry of Industry and Handicraft is responsible for providing clean drinking water in 11 provincial capitals and for approximately 60 medium and small towns. The Ministry of Rural Development is in charge of water supply in rural areas and towns with less than 1,000 households.  

Phnom Penh is a specific case in Cambodia considering its large population, which is growing very fast. Phnom Penh has around 2.5 million inhabitants while Battambang, the second largest city, has around 200,000 inhabitants. The Phnom Penh Water Supply Authority (PPWSA) has extended its supply capacity by enhancing water treatment plants and building new facilities. The water is extracted from the Tonle Sap and Mekong Rivers. In addition, PPWSA has planned the construction of the largest water treatment plant in Cambodia (Bakheng project) in 2 phases, in order to meet the growing demand expected by 2025. The plant’s total capacity will be around 400,000m³ per day, and it will cost US$ 247 million. The European Investment Bank has contributed to the funding. To achieve its development plan, PPSWA organizes international tenders regarding equipment supplies and consulting services. These tenders represent significant business opportunities.  

Source: Phnom Penh Water Supply Authority

The treatment process involves hydraulic mixing (lime, alum and chlorine), flocculation (mechanical mixer), sedimentation (rectangular basin), rapid sand filtration (fine sand), and disinfection (chlorine). Storage tanks and high–lift pumps are used for distribution. The drinkable water has the same quality standards as many developed countries and the distribution system is relatively modern. The PPSWA has succeeded in developing in-house expertise with the support of international donors to enhance the whole supply system. As a result, water losses due to leakages in pipes and pumps declined from 72% in 1993 to 6% by 2008, which is very low by international comparison. In 2010, the PPSWA obtained the Stockholm Industry Water Award for its impressive results. The PPSWA managed to become entirely self-sustainable as it benchmarked itself against the best operators in both developing and developed nations. The PPSWA is now listed on the Cambodian stock exchange.  

In rural areas and provincial cities, the development of infrastructure will rely on the funding of international donors. The Asian Development Bank (ADB) and the World Bank (WB) are particularly involved. The priority for the Royal Government of Cambodia is to complete the access to clean water supply in rural areas by 2025.  

Wastewater Treatment

Wastewater treatment is not yet well developed in Cambodia and most of the discharged water in Cambodia is not properly treated before being released into the main water bodies. Only a few cities have wastewater treatment facilities: Siem Reap, Sihanoukville, Battambang and Phnom Penh. In addition, the city of Phnom Penh still often experiences flooding during the rainy season due to its fragile sewage and drainage system. There are small sized natural lagoons that receive wastewater from the drainage system, but they are not sufficient to address the wastewater management issues. Taking this into consideration, the current situation is expected to change due to tourism development, the expansion of Cambodia’s major cities and a greater role of international donors.  

Recent public statements indicated that the number of wastewater treatment plants is to increase significantly in the future. In Phnom Penh, JICA (Japanese International Cooperation Agency) will finance a US$ 25 million wastewater treatment with a capacity of 5,000m³ per day; a memorandum of understanding was signed between Phnom Penh Capital Administration and Japan International Cooperation Agency (JICA) to build this facility. In addition, ADB is financing a project to implement a new wastewater treatment plant and new sewers in Battambang, a septage management system in Kampong Cham, expansion of the existing wastewater treatment system in Sihanoukville as well as a new trunk sewer in Siem Reap. There are initiatives from the private sector to build wastewater treatment facilities as part of their CSR strategy. These facilities are small–scale but are encouraging better practices at a reasonable cost.  

The Ministry of Public Works and Transport (MPWT), which has the responsibility of managing wastewater, has issued an action plan f. In addition, a draft law on Wastewater and Drainage is being discussed by the Royal Government to improve sewage management and wastewater treatment systems. The upcoming projects will rely on the involvement of international donors, (in particular ADB and WB,), which will fund international tenders which can represent significant business opportunities. In June 2020, the Royal Government requested a loan of US$ 55 million from the WB to improve water supply and sanitation systems. A part of this loan will be used in Siem Reap to build a drainage network that will connect the current sewage system to every household and business in the area.