Clean water is a necessity for life. People need clean, safe, purified water to survive and without it things start to look very grim, very fast. Even though Earth is covered with this precious liquid, much of it is not suitable for human consumption either because of industrial waste or natural dangers like microorganisms. To ensure clean drinking water for all water purification is compulsory for any water source.
Water purification is the process of removing undesirable chemicals, materials and biological contaminants from ‘raw water'. Raw water is essentially water that is drawn from a stream, lake or dam that has not been treated in any way. Naturally occurring water contains all manner of minerals, particles and organisms that may not make it fit for human consumption. The process of turning raw water into purified water involves quite a few steps.
Most global municipalities follow rather standard water purification process with a few regional differences dependent on local conditions. The methods most commonly employed are physical (filtration and sedimentation), chemical (flocculation and chlorination) and electromagnetic radiation (commonly UV radiation). The process for creating purified water follows strict standards and should be performed on all water no matter what the source.
Water purification usually starts with a process called flocculation. This process clarifies the water, removing turbidity or discolouration. The process adds reagents to the water that causes precipitates to form. These precipitates can then easily be removed with physical methods like a coarse sand filter before moving on to the next stage of creating purified water.
Sedimentation often takes place in a large tank or basin with a slow water flow. This allows any remaining precipitate to settle on the bottom of the basin. The amount of sediment that falls out depends on the depth of the basin and the time the water is in the basin. For standard water purification processes, this time is about four hours.
The last step of water purification is filtration. This removes all but the smallest of the remaining particles in the purified water. The water moves vertically through a filter of activated carbon and sand. The carbon removes most of the organic compounds while the sand tries to remove as much of the particulate matter as possible.
Disinfection follows the various filtration processes of water purification. The aim is to filter out or destroy pathogens, bacteria, viruses and protozoa that may be lurking in the water. The most common methods for disinfection include chlorine, ozone and UV radiation. While ozone treatments and UV radiation leave no traces in the purified water, these methods do not leave any residual disinfectant in the water which leaves it open to contamination later down the line. Chlorination, on the other hand, while effective leaves the water with a particular smell and taste.
Water purification has been developed over the centuries to be the effective process that it is today. The goal has always been to produce purified water that is not just safe to drink, but good to drink as well. While past methods left the water with acrid aftertastes or chemical smells, modern methods have succeeded in making water as odourless and colourless as possible. Nothing but pure, clean water.