Treatment of Spring Water Through Slow Sand Filtration - A Simple Cost Effective Technique

Gravity Spring in hilly areas is usually a water flow through fissured rocks. The potential environmental impact of developing a spring including risks of landslides, erosion, human activities can cause contamination of the source. So the design and construction of springfed potable water supply for a specific location is essential. The major components in design of the system include the actual spring collection area, where water from aquifer is actually being channeled to a single discharge point, supply pipe, collection chamber and the outlet to a storage tank. The design must be appropriate to the specific local conditions, prevent pathogenic contamination and pollution, have no adverse environmental impact and be reliable in terms of quantity. Safe drinking water for the people in rural hilly areas, who are deprived of getting treated spring water supplied by the state department/municipality, can be reached through filtration with Slow Sand Filter (SSF). The SSFs remove bacteria as well as small particles from water, making it safe to drink. This is a constant supply of clean, running water using simple technology. In association with Horizontal Roughing Filters (HRF), SSFs have been used very effectively for cleaning of turbid spring water as roughing filters separate solid matter from the water and improve the efficiency of sedimentation tanks significantly. If the grain size in HRF is around 0.1 mm in diameter, it may remove almost all fecal coli forms and virtually all viruses. SSFs usually require neither chemicals nor energy inputs and the capital as well as operational costs is very low comparatively. Maintenance costs will include minor repairs to the filters and replacement of sand washed out or removed during the scraping of silt from filter surface. Due to simplicity of its design and operation, SSFs can be built and used with limited technical supervision in the vicinity of hilly spring outlet. However, the improvement in water quality brought about by slow sand filtration will differ from place to place due to raw water quality, sand grain size, filtration rate, temperature and the oxygen content of the water.