Description: Segment 1 The process of collecting waste from homes and industry is explained using an animation of a town and its sewage pipes. The main, collecting sewer is shown leading away from the town. Direct disposal of sewage into the ocean is shown using a map. A pipe is shown leading onto the sea bed, and the intertitles note that where the water is shallow, sewage is stored in tanks and discharged with the ebbing tide. Shots of the ocean follow. Next, the process of sewage purification is shown. An animation shows the process of sewage travelling down the collecting sewer into the purification plant. Each aspect of the purification plant is looked at. First, the screens, which filter the water as it passes through them. These are shown and also an animation explains how they work. Rotating screens follow, which remove finer solids. Next, the Imhoff tank is looked at. An animation shows how they work. Time start: 00:00:00:00 Time end: 00:06:41:09 Length: 00:06:41:09 Segment 2 Next, the sludge beds are explained. The solid waste is shown being carted away. The liquid sewage is further purified by sprinkling filters, and these are explained in an animation. The intertitles describe how to use them efficiently. Finally, after passing through the purification plant, the filtered sewage is passed into a brook and further purified by sand filtration. An animation explains how the sand filtration works. The water is tested and looked at under a microscope. The brook water is also tested. Time start: 00:06:41:09 Time end: 00:13:30:16 Length: 00:06:49:07