A lot of ground water is naturally filtered as it travels through layers of the earth into underground reservoirs called aquifers. Water that suppliers pump from wells commonly contains less organic material than surface water and may not need to go through any or all of the treatments available. The quality of the water will depend on local conditions. The most common drinking water treatment, considered by many to be one of the most important scientific advances of the 20th century, is disinfection.
(A lot of|The majority of|Most} cj filters suppliers add chlorine or another disinfectant to kill bacteria and a selection of germs. Water suppliers use other treatments as desired, according to the quality of their source water. For example, systems whose water is contaminated with organic chemicals can treat their water with ultra violet treatment, which will aid greatly in purification of the water.