Band 9: The diagram below shows how a simple water filter is constructed and how it functions to produce clean drinking water. Summarise the information by selecting and reporting the main features, and make comparisons where relevant. » Write at least 150 words.

The diagram illustrates the construction and function of a simple water filter designed to produce clean drinking water.

The filter consists of two tanks connected by a pipe. The upper tank, which holds the untreated water, is filled with three layers of filtering materials: gravel, sand, and charcoal. These layers are arranged in descending order of particle size, with the largest gravel at the bottom and the finest charcoal at the top.

When untreated water is poured into the upper tank, it flows through the layers of filtering materials. The gravel layer removes large debris, while the sand layer traps smaller particles. The charcoal layer, with its porous structure, absorbs dissolved impurities and chemicals, further purifying the water.

As the water is filtered, it passes through the connecting pipe into the lower tank. This tank serves as a reservoir for the clean, drinkable water. The process effectively removes contaminants from the raw water, making it safe for consumption.