Collecting and cleaning rainwater

The diagram shows a six-stage process in which rainwater collected from a roof is cleaned and stored for drinking.

Overall, the water passes through two filters and a light treatment before it reaches the taps, and it is stored in a tank at two points in the process.

First, rain falls on the roof and runs into the gutters. The gutters carry the water to a filter that removes leaves and other large pieces of rubbish. After that, the water flows into a large underground tank, where it is stored.

When it is needed, a pump moves the water from the tank to a treatment unit. There, a sand filter takes out small particles, and then ultraviolet light kills bacteria. Finally, the clean water is held in a second tank, from which it is sent to the taps in the house. Altogether, the water is filtered twice, once to remove large objects and once to remove small ones, before it is disinfected.

Why it works

• A process answer uses sequence words (first, after that, then, finally) and mostly the passive voice.
• The overview says how many stages there are and what the main idea is.
• No personal opinion is given, because task 1 is only a description.