Question

how to control water pollution

Answer 1

We can prevent pollution in river water in many ways and some of them are as follows:

not discharging untreated sewage and other industrial waste water into riversnot dumping solid wastes, garbage and medical wastes in river banksnot using river banks as open toiletsnot disposing dead human bodies/animal carcasses in riversnot quarrying sand in river beds which is a key factor in river bank stability and erosion of banksnot washing vehicles directly in the flowing river waterand in many other ways according to the life style of local people


River pollution can be controlled by: 

Reducing agricultural run-offPreventing or treating industrial dischargesPreventing or treating municipal sanitary sewage dischargesPreventing or treating municipal storm water dischargesPreventing or controlling resource recovery in river channelsControlling shipping (ballast, swage) dischargesControlling marina operations 
Most fresh water pollution is caused by organic material. Humans bring organisms from one body of water to another causing aquatic plants and animals to die. Littering, sewage, food waste and farm effluent also cause under water plants and animals to die.Some other kinds of water pollution are industrial waste, fertilisers, oil and warm water. If large amounts of fertiliser or farm waste drains into a river or lake, the algae uses these substances to grow rapidly, turning the water green. Chemical waste is sometimes discharged into lakes and rivers. Some of these pollutants include: cyanide, zinc, lead, copper, cadmium and mercury. If oil enters either a slow moving river or a lake, it causes the surface to turn rainbow colours which prevents oxygen from entering the water. Industry often uses water for cooling processes, sometimes discharging warm water back into rivers or lakes. Making the water warmer makes the level of dissolved oxygen lower.

Answer 2

Avoid using the toilet as a wastebasket. Most tissues, wrappers, dust cloths, and other paper goods should be properly discarded in a wastebasket. The fiber reinforced cleaning products that have become popular should never be discarded in the toilet. Avoid using a garbage disposal. Keep solid wastes solid. Make a compost pile from vegetable scraps. Install a water efficient toilet. In the meantime, put a brick or 1/2 gal container in the standard toilet tank to reduce water use per flush.
1) control factory affluents to mix with water

2) don't throw any kind of waste into water