As Britain was the first country to industrialize, it was also the first to experience the disastrous consequences of major urbanisation and was the first to construct a sewerage system as we know it today to mitigate the resultant unsanitary conditions. Joseph Bazalgette designed an extensive underground sewerage system that diverted waste to the Thames Estuary, downstream of the main centre of population. Six main interceptor sewers, totalling almost 135 miles (217 km) in length, were constructed. The intercepting sewers, constructed between 1859 and 1865, were fed by 450 miles (720 km) of main sewers that, in turn, conveyed the contents of some 13,000 miles (21,000 km) of smaller local sewers. With only minor modifications, Bazalgette's engineering achievement remains the basis for sewerage design up into the present day.