Dr. Md. Salequr Rahman
Dep. Of Community Medicine
What is water?
Water is made of tiny molecules of hydrogen and oxygen.
Each one is so small that you can’t see it even with the
most powerful microscope.
Pure water has no colour , no taste and doesn’t smell of
Water exists in three forms on the Earth:
> solid (ice, hail, snow or frost)
> liquid (in lakes, oceans, rain, dew, fog or mist)
> gas (steam or water vapour - "invisible" water in the air).
What Is Water Pollution?
Any chemical, physical or biological change in the
quality of water that has a harmful effect on any living
thing that drinks or uses or lives (in) it.
When humans drink polluted water it often has
serious effects on their health.
Types of Water Pollution
Surface Water Pollution
Wa y s T o
Pr e v e nt
Wisely observe which nutrients are
required on the yard before fertilizers
Wisely choose alternatives methods.
Do not throw rubbish in the sewage or
any water passage.
Follow the law.
Do not litter.
Run your clothes washer and dishwasher only when they
are full. You can save up to 1,000 gallons a month.
Monitor your water bill for unusually high use. Your bill
and water meter are tools that can help you discover
Shorten your shower by a minute or two and you'll save
up to 150 gallons per month.
Use sprinklers for large areas of grass. Water small
patches by hand to avoid waste.
Collect water from your roof to water your garden.
Why should we save water?
Of all the water in the world, only 3% is fresh.
Less than one third of 1% of this fresh water is
available for human use.
The rest is frozen in glaciers or polar ice
caps, or is deep within the earth, beyond our
To put it another way, if 100 liters represents
the world's water, about half a tablespoon of it
is fresh water available for our use.
The water evaporates from the rivers, seas, lakes and forms
clouds. When the temperature decreases the water vapor
becomes liquid and rain occurs. Water returns to the surface.
The Water In Our Lives
Water is one of the
nutrients. Our body is
made up of at least
60% of water.