A glance at the diagram depicts some striking information about the process in which impure/ polluted/ contaminated/ dirty water is filtered/ purified/ treated.

It is evident from the information supplied that there are several main steps involved in the process. It starts with (N + Vpii) dirty water collected and ends with drinking water produced.

Looking at the components of the system in more detail, people prepare a plastic barrel and a storage drum which are positioned next to each other with the former placed higher than the latter. The barrel is covered with a plastic lid. Moreover, people put 3 layers including sand, charcoal and gravel into the bottom of the barrel. There is a small tube/ pipe which runs from the bottom of the barrel to the side of the drum. On the lower part of the side of the drum, people install a tap.

Regarding the process of filtering water, at the beginning, dirty water is poured into the barrel. Then, it runs through the filtering layers which help keep substances. After that the clean water is sent to the drum via the tube. When people open the tap, the clean water flows out, ready for consumption/ use.