The diagram illustrates the structure of a slow sand filter and how uncleaned water is purified by it. Overall, the structure has three main parts, namely a raw water storing, a filtering system and a freshwater storing space. Its core working principle involves leading the dirty water through the cleaning part and stored.
Regarding its structure, in the first part there is a pipe at the bottom left and a gap at the top right which connect with the second part. The biggest part containing different layers from upper to bottom consist of dirt and particles, sand which range between 60 and 90 centimetres in height and graver from 20 to 30 centimetres in depth. Below this part, there is a pipe lead to the storing section which has another pipe leading to outside the system.
Moving to the operation mechanism, first untreated water flow to the first part and at a certain level the water overflow to the second section. In there, water then goes through three layers and goes to the next part through underdrains. The treated water is then stored and lead out by the pipe in the third part.