IELTS Writing Task 1: How Drinking Water Is Treated

The diagram below illustrates the process by which river water is treated to make it safe for drinking. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The process is linear and consists of six stages. First, water is pumped from a river into a large intake tank, where a metal screen removes leaves, litter and other large objects. The water then flows into a settling tank, in which sand and heavy particles sink to the bottom and are taken away. Next, the water passes through beds of fine sand and gravel that filter out smaller impurities. After filtering, chlorine is added to the water to kill any remaining bacteria. The treated water is then stored in a covered reservoir before finally being pumped through underground pipes to homes and businesses.