Water Purification

In Scotland, we take access to fresh, clean drinking water for granted; it is literally available 'on tap'. However, for others around the world, access to safe drinking water is a daily struggle. 

One in four of people on Earth do not have access to safe drinking water, but as seen previously with food, this average varies greatly from country to country : 

The videos below show an introduction to the topic of Water Scarcity:-

As can be seen in the diagram below, several countries across the Middle East, North Africa & South Asia have extremely high levels of water stress. Many, such as Saudi Arabia, Egypt, United Arab Emirates, Syria, Pakistan, Libya have withdrawal rates well in excess of 100 percent. This means they are either extracting unsustainably from existing aquifer sources, or producing fresh water artificially :

The Health Effects of Water Scarcity

Water is required for all essential processes of life; Humans can survive only approximately three days without water. The NHS guidelines state that, on average, a person requires approximately 2 litres of water per day. Less than this, and a person becomes at risk of 'Dehydration'. 

Getting Clean Water ( Developed countries )

In developed countries, water that has been extracted from aquifers, rivers or lakes will be purified before use at a water treatment plant : 

In some countries, the chemical 'fluoride' is added to the tap water before it is distributed to homes. The fluoride is added to tap water to help prevent dental cavities :  

Getting Clean Water ( Developing countries )

In less developed parts of the World, however, access to water can be much harder to access. 

In the absence of a centralised 'mains water' supply, water is commonly collected from wells, lakes or rivers and undergoes minimal purification before use. 

This can lead to a range of consequences to health, caused by microbes or other contaminants, but some steps can be taken to reduce the risk  : 

Water-borne Disease Case Study : Cholera 

Cholera is an acute diarrhoeal infection caused by consuming food or water contaminated with the Cholera bacterium. It is estimated that every year, there are 1.3 to 4.0 million cases of cholera globally, and 21,000 to 143,000 deaths worldwide due to the infection.

Cholera outbreaks can occur anywhere where access to safe drinking water is limited, either by lack of development or in the aftermath of natural disasters or conflicts. 

The symptoms of Cholera can be easily treated using an oral rehydration solution, and education about safe water management can help reduce further outbreaks  : 

Getting Clean Water ( Emergency Filtration)

Note - The following is a theoretical method to produce safe drinking water for use in an emergency situation only. Any water purified by this method should not be consumed, as much safer alternatives will always be available in Scotland. 

As can be seen from the above case study, water taken from a river or lake can contain contaminants that can cause illness. To purify this water, several steps can be taken to reduce (not remove) the risk of illness. 

The first key step is 'Filtration'. 

If an insoluble substance (such as sand, twigs or mud) is present within a liquid, it can easily be separated from the liquid by filtering. 

Filtering uses a material which has very small holes within it (such as paper). The holes are too small for the insoluble substance to pass through, but large enough for the water to pass through. The liquid that passes through the filter is known as the filtrate. 

The steps below show how to make an emergency water filter :  

Note - The following video is demonstrating an emergency situation. This should not be repeated, unless you are literally Bear Grylls. 

Getting Clean Water ( Microorganisms )

The above process will remove most insoluble contaminants from water, but it cannot remove microorganisms. These are so small that they would be carried through the filter within the water. 

This means that even though the water looks clean, drinking it could still make a person ill. This includes Bear Grylls in the video above...

To remove the risk microorganisms in the water, two processes can be used : 

Note - The above methods can reduce the level of microorganisms in water, but be aware that some microorganisms can survive both of these processes. 

Getting Clean Water ( Desalination )

Another barrier to safe drinking water can be a lack of access to fresh water at all. 

In order to provide safe water for their residents, some countries have to process seawater into drinkable fresh water. 

Sea Water is not drinkable, due to the high levels of dissolved salt within it : 

The process of converting salt water into fresh water is known as 'Desalination'. This is usually done through a process known as 'Reverse Osmosis' : 

Getting Clean Water ( Emergency Desalination )

Note - The following is a theoretical method to produce safe drinking water for use in an emergency situation only. Any water purified by this method should not be consumed, as much safer alternatives will always be available in Scotland. 

The salt can be removed from seawater by another process - 'Distillation'. The diagram below shows pure water being 'distilled' to produce drinkable fresh water :