Water is the key to a person's survival because without water survival is simply not an option. However, water has to be purified in order to drink otherwise bacteria in the water can be harmful to your organs if drunk in normal consumption. This is highlighted especially in third world countries such as Ethiopia and Gambia where many people die due to impure water that contains lots of bacteria that cause infection and illness. In all MEDC countries there is a point at which water is considered pure and it must go through a thorough process in which the water is processed in a treatment plant until it is determined pure enough to drink (drinking water).

The process of water purification is quite complicated and once pure the water can be used for a number of reasons other than human consumption. For example pure water can be used for medical purposes as well as industrial purposes. The sources for the drinking water that an everyday person consumes can come from a wide variety of places. One example would be groundwater. This is water that comes up from underground, a result of rainfall that fell hundreds of years ago. The soil and rocks naturally filter the water while it is in the ground and that means that when the water is pumped to the treatment plant there is no need for high filtration.

Water may also be pumped from wells or boreholes in the ground if other sources may be low. This type of water though may need a high level of disinfection due to the other chemicals in it such as carbon and magnesium. Another source of water are lakes, reservoirs and canals; this water is generally high in bacteria however. This means a high level of filtration is needed to ensure that the water is pure enough to drink. Due to this being natural water there may also be algae growing on the water's surface due to fish and other natural life present in many reservoirs and lakes.

Higher filtration levels means it takes a lot longer to purify water. One last example would be to collect rainwater and fog that is natural water collected together in the atmosphere. To collect this water big water butts and man made holes are constructed allowing for a large amount of water to be held. It is considered that the water collected is not safe to drink straight away and must be put through a treatment process first before it is drunk.

There are five stages to the pre treatment process of the water. The first process is the containment and pumping stage. This involves the pumping of the water from its source into large tanks where it can be kept for a period of time. To avoid contamination of the water the pumps and buildings must be made of special materials. The second stage is the screening; this is where large objects in the water are removed such as leaves or sticks. Groundwater does not need this stage normally as it is filtered before purification.

The next stage is the storage of the water in big man made reservoirs. The water can be stored for months at a time until the water is naturally purified. Also in large periods of drought, water is kept in reserve if there is a water shortage. The fourth and fifth stages include the softening of the water as in some cases the water can be too hard due to an excess of chlorine. Also small organisms and other bacteria are removed from the water allowing the water to enter the main treatment process.

Without the scientific water purification process the developed world would be susceptible to a large variety of waterborne diseases. It is thanks to these processes that we have safe and clean drinking water. Truly water is the essence of life and thankfully the processes involved in its purification ensure our safety.