Safe drinking water is critical to the overall health of communities. When most people lived in rural areas, with wells and springs providing generally safe water, drinking water was not recognized as a major public health threat. During the Industrial Revolution in Europe and North America in the 19th century, waterborne threats increased as a result of the high density of populations that had moved from the countryside to cities seeking work. In the drive for profitable industry, little regard was given to living conditions or to the pollution that occurred as a consequence of human and industrial waste. With growing populations and associated increases in demand, more and more reliance was placed on surface waters. There was no water source protection or water treatment.