The consequence of the water crisis is very clear: dirty water is dangerous, even deadly, for our health. So, what are some ways to get rid of waste or disease-causing agents? To clean up our water? Here are some common methods:

Coagulation and Flocculation

  • Coagulation is the process that helps collect dispersed contaminants into larger groups.
    • Positively charged chemicals are added to water → They interact with the negatively charged areas of contamination in water → They then form large neutralized aggregate solids, also known as floc

  • Flocculation is the process that creates even larger, heavier floc aggregates that can more easily be removed from water.
    • A flocculant is added to a coagulated mixture and helps “stick” floc together → Smaller floc join together and become larger floc solids → Larger floc solids then sink to bottom of water due to weight



  • Water is passed through filters of different compositions and pore sizes to remove dissolved water contaminants (ex: dust, bacteria, chemicals, viruses) and larger solids (floc aggregates).

Note: filters likely require cleaning upkeep or replacement after a certain period of use

Filtration may be useful to remove contaminants from water, but once water is filtered, it is not protected from re-contamination via pathogens in the air or other containers.



  • A disinfectant is added to water to kill parasites, bacteria, and viruses, as well as protect water from germs.
  • Different types of disinfectants include:
    • Chemical: chlorine, chlorine dioxide and other chlorine chemicals, ozone
    • Physical: UV light, heat (such as boiling)


While any one method can have its own utility and success in water purification, it is important to recognize that these are all steps which, when performed together, can yield more effective water treatment. In addition, feasible water sanitation methods will depend on the community and its resources, as well as the quality of water requiring treatment.


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