<P> Living away from drinking water supplies often requires some form of portable water treatment process . These can vary in complexity from the simple addition of a disinfectant tablet in a hiker's water bottle through to complex multi-stage processes carried by boat or plane to disaster areas . </P> <P> Some industries such as the production of silicon wafers, space technology and many high quality metallurgical process require ultrapure water . The production of such water typically involves many stages, and can include reverse osmosis, ion exchange and several distillation stages using solid tin apparatus . </P> <P> Early water treatment methods still used included sand filtration and chlorination . The first documented use of sand filters to purify the water supply dates to 1804, when the owner of a bleachery in Paisley, Scotland, John Gibb, installed an experimental filter, selling his unwanted surplus to the public . This method was refined in the following two decades, and it culminated in the first treated public water supply in the world, installed by the Chelsea Waterworks Company in London in 1829 . </P> <P> As of 2006, waterborne diseases are estimated to have caused 1.8 million deaths each year . These deaths are attributable to inadequate public sanitation systems and in these cases, proper sewerage (or other options such as small - scale wastewater treatment) that must be installed . </P>

Treating water for domestic use requires the following steps