Previously in rural Cambodia the emphasis has been on accessing drinking water through ground water sources such as tube wells and surface water sources such as rivers and shallow ponds. It is now evident that not all these sources meet drinking water standards and not all areas have enough water to meet even basic needs. Problems range from arsenic and iron contamination in groundwater through to fecal contamination and pesticide residues collecting and concentrating in open ponds. During the height of the dry season some villagers must travel for up to five hours followed by long waits in queues to access the nearest water source, which may be of extremely poor quality.
Due to these issues considerable effort has been directed into treatment methods that provide "point of use" treatment for drinking water. In particular household filters such as bio-sand filtration or ceramic filters have been developed along with approaches such as solar disinfection (SODIS), chlorination and boiling. Piped water from small scale water treatment plants are now being developed for bigger villages - typically 300 plus families. These methods have proven effective in dealing with fecal contamination and some other pathogens. Unfortunately they cannot cost effectively address heavy metal contamination or remove agricultural waste products, they are also of limited benefit where insufficient water exists in the first place.
Many people throughout Cambodia already practice rain water harvesting on an informal basis collecting run off in large jars, typically of about 500 litres in capacity. Each household will have more or less of these jars depending on income level but very few have enough to reach the national standard of 3,000 litres of storage capacity per household. The jars are usually left uncovered and this can lead to the breeding of mosquitos and the growth of algae and pathogens in the jar. The large opening also encourages the use of dippers to access the stored water, a further source of contamination in villages where open defecation is considered normal.
These issues are not insurmountable however and RainWater Cambodia has been working hard over the last eight years to establish a fomalised method of rainwater harvesting providing high quality, disease and heavy metal free rain water to thousands of households, community centres and schools. We have also trained local entreprenuers to follow our risk managment approach to rainwater harvesting and they are replicating this successful programme in their own businesses.