The process of water purification is used to describe the elimination of contaminating agents to make it suitable for drinking or other uses. Using a number of different purification techniques, a device or process can remove a large percentage of the bacteria, viruses, fungal pathogens, algae, parasites, and sediment. While many people rely on simply boiling the water for a period of time, this is not a completely effective process and can leave unwanted agents still present and alive in the water. A better option is to use a filtration or purification technique that has been proven to yield good water.
The source of the water will often determine how much or what type of purification will need to be done. Groundwater sources are typically the most pure, being naturally filtered by rocks and soil to keep the prevalence of bacteria and other pathogens quite low. However, groundwater will usually have some sediment that may be need to be treated before using. Lowland lakes, rivers, and canals present a water that may have a high concentration of pathogens and thus must be suitably purified. Seawater will need to go through reverse osmosis or distillation to remove the natural salts and any harmful organisms.
Large scale water treatment for cities and other regions involves a number of steps that are important in providing a trustworthy water source. The treatment begins with an adjustment to the pH. Lime and soda ash are commonly added to bring the pH to an alkaline level that will be better for the next step of flocculation. This step will give the water a clear color and remove a large part of the suspended matter that is present. After flocculation, the water enters a basin for sedimentation, where it is allowed to rest so the sediment can flow to the bottom and be removed. Before it enters the water supply of the area, it will be filtered using sand, coal, or other materials.
In many countries around the world, the absence of a good water supply means that purification is needed. However, it is estimated that over 1 billion people are without the right machinery to make this purification of process. In addition to increasing the expenses a person must spend to obtain the right water, this contaminated water can easily help to spread diseases and sickness among the people of the region. It is thought that the vast majority of the 1.8 million cases of people who are killed by diarrheal diseases each year contract the problems because of a lack of clean water. With many portable and individual methods of purifying water, a person now has more options for making sure that they will have constant access to clean water.