Point of use water treatment

Potable water purification devices – better described as point-of-use (POU) water treatment systems and field water disinfection techniques – are self-contained, hand-carried units used by recreational enthusiasts, military personnel, survivalists, and others for water purification when they need to obtain drinking water from untreated sources (e.g. rivers, lakes, groundwater etc.). These personal devices and methods attempt to render water potable (i.e. safe and palatable for drinking purposes - without disease-causing pathogens).

Techniques include heat (including boiling), filtration, activated charcoal absorption, chemical disinfection (e.g. chlorine, iodine, ozone, etc.), ultraviolet purification (including SODIS), distillation (including solar distillation), and flocculation. Often these are used in combination.

Many commercial portable water purification systems or chemical additives are available for hiking, camping, and other travel in remote areas.

Untreated water may contain potentially pathogenic agents, including protozoa, bacteria, viruses, and some larvae of higher-order parasites such as liver flukes and roundworms. Chemical pollutants such as pesticides, heavy metals and synthetic organics may be present. Other components may affect taste, odour and general aesthetic qualities, including turbidity from soil or clay, colour from humic acid or microscopic algae, odours from certain type of bacteria, particularly Actinomycetes which produce geosmin, and saltiness from brackish or sea water.

Common metallic contaminants such as copper and lead can be treated by increasing the pH using soda ash or lime, which precipitates such metals. Careful decanting of the clear water after settlement or the use of filtration provides acceptably low levels of metals. Water contaminated by aluminium or zinc cannot be treated in this way using a strong alkali as higher pHs re-dissolve the metal salts. Salt is difficult to remove except by reverse osmosis or distillation.

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Wikipedia