When the planktonic algae grow in sufficient numbers and accumulate or cover the water surface of the water body, this condition is known as an algal bloom or water bloom. It gives a distinct colour to the entire water body. The colour of the algae determines the colour of the water blooms. It may be temporary or permanent. A large number of factors are found to be associated with the formation of water blooms. These are; water temperature, water movements, sunlight, inorganic and organic nutrients, pollution level, and heavy metals of the water body. Algae-causing water blooms are Microcystis sp., Gonyaulax sp., Gymnodinium sp., Spirulina sp., Nostoc sp., Anabaenopsis sp., Volvox sp., Zygnema sp., Pandorina sp., Chroococcus sp., Merismopedia sp., Ceratium sp., Nitzschia sp., etc. Algal blooms have a positive and negative role in our daily life.