Clean and safe drinking water is a one of the essentials of life. Around the world water has become a major issue. gravel filter remove bacteria and other small particles from water using simple and exessible technology.The water passes through this leaving suspended particles trapped in the layers. Organic sediment is eaten by microscopic organisms including bacteria and protozoans which live in the slime that forms around the sand particles. The end result should be clean water which is safe to drink – assuming there are no other types of contaminant. If the size of the grains of sand is small enough, the filter should be able to remove and most viruses and faecal coliforms (bacteria from faeces).