Translations:Water - Biosand Filter/52/en

While water is poured into the filter, the level of water (also called the hydraulic head) is elevated and pushes the water) through the diffuser and the filter. The level of water in the reservoir drops as the water flows steadily through the sand. When the reservoir is full, the output should be 400mL per minute. The output will diminish gradually since there is less pressure to push water through the filter. The water that goes through the filter contains dissolved oxygen, nutrients and contaminants. It brings some oxygen and nutrients that are needed by the micro-organisms in the biological layer. The suspended particles and large pathogens are caught in the first layer of sand and they are clog part of the pores between the grains of sand. This clogging slows the output of the filter over time. Users may occasionally resort to a ‘’’swirl and dump’’’ maintenance procedure to restore the output flow of the filter.