Water isn’t always clean.  It has to get purified (cleaned) first.  Here is how water gets purified.
 First, pipes bring the water to settling basins.  Plastic, wood, and other large objects get caught in rakes so they won’t go into the settling basin.  At the settling basins, a coagulant like alum gets added to the water to get rid of dirt and tiny plants called algae.
 Second, the water gets aired out at the aerators.  Aerators shoot the water in the air to make it smell better.  This looks like a water fountain.
 Then lime gets added.  Lime helps the water to not rust pipes as easily.  Lime is white and powdery.
 After that, the water goes to settling ponds.  Here the floc in the water settles at the bottom.  This makes the water less dirty.  Now, chlorine gets added to the water.  Chlorine helps to clean the water so the germs will disappear.
 That is how water gets purified.  We can’t live without water and we have to drink clean water.

Resources:
1. Walpole, Brenda.  Water.  Garrett Educational Corp., 1990.
2. http://www.provwater.com/watercycle.htm
3. Kalman, Bobbie and Schaulr, Janine.  Wonderful Water.  Crabtree Publishing Co., 1992.
4. Frost, Helen.  Keeping Water Clean.  Calstone Press, 1949.
5. Seixas, Judith.  Water:  What it is, What it Does.  Green Willow Books, 1987.