Out of the total water found on Earth, 0.01% of water is available for consumption.

There are three steps involved in the purification of water in treatment plants. They are sedimentation, filtration and chlorination.

Oil spills and industrial effluents affect the water bodies by increasing the temperature of water bodies.

Liquid waste from industries is commonly referred to as effluent. The waste matter which is disposed from household dwellings is called sewage.

Fluorosis is a condition in which the body suffers due to excess fluoride. It causes staining of teeth, ligament calcification, severe skeletal abnormalities, poor digestion, etc.    

 Rainwater collected on the roof-tops contains soil from the roof and other suspended matter. It is therefore filtered before it is used.

The underground rainwater harvesting tanks are the best because they capture water from various places for storage. The water from the roof as well as landscaped areas can be canalised into these tanks.  

 The main effects of heavy rainfall are:   (1) It leads to the rise in the level of suface as well as ground water.  (2) The crops in the fields and forests get submerged. However the insects, worms and other animals under ground are not significantly effected. The holes initially get filled witn water but are soon aerated again as the water seeps into deeper layers. 

Population rise, heavy industrialization and life style changes, all result in an increase in the demand for fresh water and create conditions that lead to water shortage.

The basic idea behind rainwater harvesting is "catch the water where it falls" e.g collecting it from the roof tops and low lying areas and the using it for variuos purposes or to recharge the water table.

Chlorination is a commonly used chemical method for purifying water. It is done by adding chlorine tablets or bleaching powder to water.

Flood leads to the loss of life and property. With the advanced technology communication is not significantly disrrupted as satellite links are not effected by floods.

Rainwater harvesting is done to ensure the availability of water and to collect or store it for later use. This water can be later used for drinking( after purification) and other purposes like irrigation.

The chemicals released in water during industrial processes include arsenic, lead and fluorides. They contaminate the water and cause toxicity.

Phytoplanktons are photosynthesising microscopic organisms that inhabit the upper sun-lit layer of almost all oceans and freshwater bodies. Thus, growth of phytoplanktons in water bodies is not responsible for water pollution.