Summary of Groundwater Quality in Cambodia
– Data, Maps, and Priority Parameters
Resource Development International Cambodia August 2009 Updated March 2011 Updated March 2012
Tube wells (also known as boreholes) and open wells (also known as dug wells) are common throughout Cambodia (see Well Types page) and provide rural Cambodians with groundwater for drinking, cleaning, bathing, and agricultural activities. The quality of the water these sources provide can vary depending upon the presence of natural and human-caused contaminations. Deeper wells are often safer from the impacts of human activity at the surface but may have a higher risk from contaminations that are naturally found in the ground. These contaminations can cause health problems or may make the water taste or look bad. Shallow wells can be safer from naturally-occurring contaminates like Arsenic, but have a higher risk from contaminations associated with human activity at the surface, such as faecal waste. Surface waters and shallow aquifers can become contaminated when rains wash through faecal waste and subsequently through or along the ground. Because there is little human and animal waste management in Cambodia, surface waters (rivers, streams, lakes, and ponds) and shallow groundwaters are usually contaminated with faecal pollution (microorganisms such as viruses, bacteria, and protozoa). However, harmful microorganisms called pathogens are much more easily removed (boiling, ceramic/bio-sand filtration, disinfection) than chemical contaminants such as Arsenic, Manganese, Fluoride, Nitrate, and Iron. Rainwater is also heavily relied upon in Cambodia and is often the preferred water source because of its look and taste. If stored well and in sufficient quantities, rainwater can provide the safest and most reliable source for drinking water in rural Cambodia. Piped water systems are also emerging in areas where population density and general wealth are sufficient to sustain these systems
Since 2005, RDI has been conducting groundwater surveying activities from province-to-province, collecting samples and analyzing them in our laboratory. Over 10,000 wells have been tested in five priority provinces. Some areas have been found to have unsafe levels of Arsenic, Manganese, Fluoride, and Nitrate which can cause serious impacts to human health. Many areas have high Iron, Turbidity, Hardness, etc. which do not impact human health but may make the water taste and look bad, damage clothes, or cause rice to turn colour when cooked. The following sections present general water quality conditions and trends observed as part of these surveying activities.
Iron concentrations are generally very high in the groundwaters of Cambodia. Iron is naturally-occurring but has no health effects when consumed through drinking water. Iron can cause the water to look cloudy, taste poor, and can stain laundry or discolour rice. The drinking water quality standard for Iron is 0.3 mg/L based on aesthetic effects, but this is often exceeded in groundwaters. Figure 7 presents areas where Iron has been observed to be elevated in the groundwater.