WATER POLLUTION: when the QUALITY or composition of water changes directly or indirectly as a RESULT of man's activities such that it becomes unfit for any purpose it is said to be polluted.Water pollution is the contamination of water by foreign matter such as micro-organisms,chemical,industrial or other wastes,or sewage.It can also be defined as"the addition of anysubstance to water orchanging water's physical and chemical characteristics in any way which interferes with its use for legitimate purposes".Signs of polluted water:1.Bad taste of drinking water2.offensive colours from lakes,rivers and ocean beaches.3.unchecked growth of adequate weeds in water4.decrease in numberof fish in fresh water and sea water5.oil and grease floating on surface OFTHE water**SUCH POLLUTED WATER CANT B USED FOR PUBLIC SUPPLY,RECREATION AND AESTHETICS,FISH,OTHER AQUATIC LIFE,WILDLIFE,AGRICULTURE AND INDUSTRY.MAJOR WATER POLLUTANTS:sediments consistingof soil and mineral particles washed by storms and flood water from croplands,mine working,roads etc.2.sewage,waste from animal feedlots,papermills,etc.3.petroleum,especially from oil spills4.radioactive substances from the wastes of uranium and thorium MINING and refining,from nuclear power plants,etc.5.inorganic chemicalssuch as acids,household cleaning agents,heavy metals and salts such as:lead and mercury from industrial effluents.6.inorganic nutrient such as substances like nitrogen and phosphor from animal wastes,plant residues and fertilizerrun off.