IELTSライティング Task 1: バンド8.5 エッセイサンプル — 環境

The diagram illustrates the five-stage process through which rainwater is collected and purified to supply drinking water to households in an Australian town. Overall, the process moves in a clear linear sequence, beginning with the collection of rainwater from rooftops and ending with the delivery of treated, potable water to each home. In the opening stage, roof drainage systems are installed to capture falling rainwater, which is then guided along channels and into pipes that lead directly to a water filtration unit. Here, physical contaminants such as leaves, sediment, and larger particles are effectively removed, marking the completion of primary filtration. The filtered water subsequently flows into a large storage tank, where it is held temporarily before being transferred to a separate treatment tank. In this final purification stage, precisely measured chemical substances are introduced into the tank to eliminate bacteria, pathogens, and any remaining impurities, ensuring the water is safe for human consumption. Once the chemical treatment is complete, the fully purified drinking water is pumped from the treatment tank and distributed to every household through a network of underground pipes.