The given diagram gives information about how contaminated water is filtered by using a slow sand filter.
Overall, the apparatus consists of two main parts and utilizes sand and gravel to convert raw water into a consumable one. The system is simple and budget-friendly, yet rather effective at producing purified water.
In the first chamber of the system, a bottom inlet channels raw water into it. This chamber is called the ‘break pressure chamber’, where unpurified water is stored and gradually flows into the adjacent section thanks to the difference in pressure.
When reaching the second section, the water slowly passes down two distinct layers. The first layer contains fine sand, from 60 to 90 cm thick, while the second one encompasses gravel, with a thickness of 20 to 30 cm. As water flows down, particles and dirt are absorbed by such material layers, resulting in drinkable water. The fresh outcome is collected by a drain located at the bottom, which can then be distributed to consumers through an outlet.