With the help of a few simple resources, it is possible to build your very own water filtration system. This is not necessary in first world countries where clean water is distributed to homes, however, in rural areas where clean water is scarce, it is important to have proper filtration methods to clean the water.
First, let’s look at different water filtration methods. One of the most effective treatment methods is chlorination. When dirty water is treated with chlorine at high temperatures, the bacteria in the water is killed along with other microorganisms which may contaminate the water. If this process is done without the use of too much chlorine, the water should be purified and safe to consume.
Another method is the use of activated carbon to treat dirty water. In this process, the dirt and soil particles stick to the surface of the carbon as the water passes through the layer of carbon. The water produced from this method still contains a lot of impurities and is not suited for consumption.
It is quite difficult to implement the processes mentioned above into a regular house because activated carbon and chlorine cannot be obtained easily. Therefore, to create your water filtration system, simpler methods need to be used. The simplest processes are sand filtration and distillation. The water produced at the end of these processes are quite clean but may not be clean enough to drink. It can be used for all other purposes, however, such as cleaning, washing and irrigation.
Irrigation is the supplying of water to the soil in order to cultivate healthy crops. This is very useful for areas where agriculture is important, but the rainfall is not enough.
Let’s take a look at a particular example in the village of Sandikhola in Nepal:
Water filtration systems in rural areas
The village of Sandikhola is a hilltop community located in the Gorkha district of Nepal. During the dry season, local water sources do not provide enough output to support the village, and people are forced to walk long distances to retrieve water for household purposes.
Nepal mountain village. Source: Gettyimages
The current facilities available in Sandikhola do not allow for multiple uses of water during the dry season. There is a lot of grey water present in Sandikhola. Greywater is the waste water leaving domestic households (kitchens, gardens, etc.) excluding sewage water (water from toilets).
A sand filter combined with a distillation system is perfect for an area like Sandikhola, which does not have enough money to buy a new water filtration system. With a sand filter/distiller system, grey water exiting houses in these areas can be treated so that they can be reused for washing clothes/bodies and for irrigation.
Irrigation with untreated grey water has been shown to increase growth, yields and nutrient content compared to plants irrigated with tap water. However, excessive use of untreated grey water can have a harmful effect on soil including increased salt levels.
The sand filter/distillation system
A sand filter is a tank of sand where bacteria can collect at the surface. As the layer of bacteria grows on the surface of the sand, a biofilm begins to form. A bio-film is a layer of microorganisms which include bacteria. The bio-film continues to grow by feeding on waste matter. In other words, the bio-film decomposes waste such as organic matter (usually present in the water exiting a kitchen because it contains food particles and oils).
Therefore, when dirty water is passed through a sand filter, the bio-film will trap the food and oils present in the dirty water and decompose it. The water will filter through the gaps in the sand but the bio-film will not move since it’s too large to move through the gaps in the sand. The water will exit at the bottom of the tank of sand. The water can be collected from the bottom and then distilled.
Distillation is a simple process where water is heated above its boiling point. Water boils at 100oC and turns into water vapour. Once the water leaves the sand filtration tank, it is heated and the water vapour is passed through a glass tube. As the water passes through the tube, it starts to cool and condenses. Condensation is the process when water vapour changes back into a liquid as it loses heat.
Any glass tubing can be used to capture the water vapour and then a basin can be placed at the end of the tube to collect the water that condenses.
In this manner, grey water, which is water exiting the household can be cleaned and purified using a sand filter and a distillation system. The treated water is not clean enough to drink, however. This is because tiny microorganisms present in the dirty water will not be removed. However, the water can still be used for watering the garden and cleaning/washing.
Therefore, grey water which leaves your house can be recycled to clean your car, your house and even to water your garden!