Thames

The Thames has always been the main source of drinking water for the people along its banks and, since the 19th century, for Greater London as a whole. At the same time, the river has been used as the city’s sewage and industrial waste outlet. This problem was first addressed by the sewage system devised by Joseph Bazalgette and built between 1859 and 1875, which diverted all domestic sewage and rainwater in a unified system of drains to outfalls further downriver. Tides delayed the dispersal of the waste, however, and industrial pollution direct into the river continued until by 1949 the Thames in London had become completely devoid of oxygen. Stringent standards on the purity of all effluents have since 1964 raised the quality of Thames water.

By 1974, when the Port of London Authority handed over pollution control to the new Thames Water Authority, 82 species of freshwater and sea fish were to be found in waters previously inhabited only by the occasional eel. By the year 2000, this had increased to over 100 species.

In 1984 a moveable barrier to protect London from floods caused by extreme high tides and a rising sea level was opened by Elizabeth II at Woolwich. The Thames Flood Barrier consists of six steel gates each weighing up to 1,500 tonnes that are rotated 90° into position from beneath the water.