**Sources of Water:**
– Groundwater naturally filtered by soil and rocks
– Upland lakes and reservoirs located away from human habitation
– Rivers, canals, and low land reservoirs with significant bacterial load
– Atmospheric water generation technology extracts water from the air
– Rainwater harvesting and fog collection in dry areas
**Treatment:**
– Various techniques available to remove contaminants
– Water purification plants commonly use specific processes
– Pretreatment involves pumping, screening, and storage
– Pre-chlorination and pH adjustment are part of the treatment process
**Goals of Treatment:**
– Remove unwanted constituents and make water safe to drink
– Techniques vary based on water quality and cost
– Methods used depend on quality standards expected
**Pretreatment:**
– Water pumped from source into pipes or tanks
– Screening removes large debris from surface water
– Storage in reservoirs allows natural purification
– Pre-chlorination discontinued due to quality effects
– pH adjustment important for water purification processes
**Drinking Water Treatment Processes:**
– Filtration, sedimentation, and distillation
– Slow sand filters and biologically active carbon used
– Chemical processes like flocculation and chlorination
– Ultraviolet light and electromagnetic radiation utilized
– Standards for drinking water quality set by governments or international bodies
Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption (drinking water), but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.
Water purification can reduce the concentration of particulate matter including suspended particles, parasites, bacteria, algae, viruses, and fungi as well as reduce the concentration of a range of dissolved and particulate matter.
The standards for drinking water quality are typically set by governments or by international standards. These standards usually include minimum and maximum concentrations of contaminants, depending on the intended use of the water.
A visual inspection cannot determine if water is of appropriate quality. Simple procedures such as boiling or the use of a household activated carbon filter are not sufficient for treating all possible contaminants that may be present in water from an unknown source. Even natural spring water—considered safe for all practical purposes in the 19th century—must now be tested before determining what kind of treatment, if any, is needed. Chemical and microbiological analysis, while expensive, are the only way to obtain the information necessary for deciding on the appropriate method of purification.