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Environment and health
The living environment, especially human health, is affected by the discharge of untreated and low quality treated wastewater. Major urban sanitation problems in Cambodia are technical, financial and institutional. There is no public investment in public infrastructure dedicated solely for sewage. The existing storm drainage system is also used for sewage collection and conveyance. Existing septic tank systems are inadequate and are required by law to be installed in all new buildings. Therefore, the waste from these septic tanks flows into the storm drainage system for discharge into receiving waters without any treatment, thus creating potential environmental pollution problems (WEPA, 2010). Only some effluents from the industrial sector are treated before being discharged into a sewage system and finally to the receiving sources (Sokha, 2008).
During the rainy season, there is enough dilution water to eliminate or reduce pollution in the receiving bodies of water. During the dry season, the drains mainly convey sewage and the concentration of pollutants is higher than in the rainy season, because raw sewage is discharged into the receiving bodies of water at a time when they would have lower amounts of water for dilution. There are reports that the above-mentioned situation is causing growing pollution in the Mekong river and other main water bodies.
A second problem with the sewerage systems is that they are not designed to prevent the deposition of solids within the storm drains during the dry season when they convey only sewage. Hence, organic solids (such as excreta) tend to be deposited in the drains during the dry season. The decomposition of these solids causes widespread odours at street inlets to the drains. It also generates corrosive gases such as hydrogen sulphide that attacks concrete storm drains, thus shortening their design lives because of premature deterioration.
Problems are not only limited to the dry season, however. There are reports that during wet seasons a mixture of sewage and storm water often backs up into houses in low-lying areas. Lack of awareness of alternative solutions to urban sanitation problems is another significant issue for urban sanitation in Cambodia. Another problem is lack of access by the poor to public storm drainage systems used as combined sewerage for both storm water and sewage. For the poor, the cost of connecting to storm drains is too high. Commercial forestry, agriculture and mining also affect the country’s surface water system (WEPA, 2010).
The outcomes of analyses of water samples in 2001, 2002 and 2003, taken from designated sampling points in the Mekong, Tonle Sap and Bassac rivers, have shown that these natural water sources are generally less polluted than in other riparian countries. During the rainy season (July to October) the river water is turbid with a high concentration of silt resulting from soil erosion in the upstream and local catchment areas. In the dry season, especially in April, BOD values noticeably exceed water quality standards for public water areas set by the Ministry of Environment. Coliform also increases from February to July (WEPA, 2010).
Groundwater quality is generally satisfactory. However, unpalatably high iron levels are found in about 10 percent of the tubewells, particularly in Kandal Province. Increased salinity is seen in parts of the southernmost (delta) provinces, most likely the result of contamination by salt contained in the original deltaic deposits, and recent measurements indicate that water drawn from aquifers in some locations may cause health problems because of the high concentration of chemical substances. However, the status of groundwater contamination is not widely disseminated owing to a lack of human resources, analytical facilities, technical skills, etc. (WEPA, 2010).
ADB provided nearly US$11 million for a new wastewater and sewerage treatment facility in Siem Reap to help end bouts of serious flood in the country’s biggest tourist destination. The project was inaugurated recently in Siem Reap, which has been subjected to frequent floods in the central commercial and tourist accommodation areas, because the old and defective drainage and sewerage system was unable to cope. The project includes the construction and installation of thousands of meters of sewer lines as well as the rehabilitation of more than 2 100 m of drainage pipes. The defective drain covers in the city’s centre have been replaced and irrigation canals upgraded (Dap News, 2010).
Two of the most common water-related diseases linked to the development of irrigation are malaria and schistosomiasis. Malaria is already a serious problem throughout the country because of the natural ecosystem. In 1999, estimates of about 500 000 cases of malaria per year were common. Each year, 5 000-10 000 people die from malaria. Schistosomiasis was reported in the Kratie area in 1993. Dengue fever became, in the 1990s, an important cause of child morbidity. In 1990, about 7 000 cases resulting in 340 deaths were recorded.