Name: __________________________
BCS 448 – 7th grade Science
Separating Mixtures – What’s in your water?
Class #_________
Date: __________
Water (H2O) alone is a pure substance compound. However, in nature, water is rarely found to be
100% pure. For example, sea and ocean water has salt and other minerals in it. Water can also have dirt
particles, sand sediments, and other contaminants (germs, dirt and waste) from animals and plants inside
it. Water treatment companies usually purify water as much as possible through a process that separates
the H2O molecules from the different contaminants. Groundwater is water located under ground and
typically requires less treatment than water from lakes, rivers, and streams.
The first step is pumping water from their source, such as streams, lakes, rivers and reservoirs to
the water treatment factory.
Next is a step called Coagulation (co-ag-u-la-shun), which is the process of that uses chemicals to
cause the larger contaminants suspended in water attract and clump together. These clumps of
contaminants is called “floc.”
The third step is called separating the mixture of water and floc in a process called Clarification
(clar-if-i-cay-shun). The heavy particles (floc) settle to the bottom and the clear water moves to filtration.
The fourth step is called Filtration (fill-tray-tion). The water passes through filters, some made of
layers of sand, gravel, and charcoal that help remove even smaller particles.
The fifth step is called Disinfection (dis-in-fect-shun). A small amount of chlorine (Cl) and ozone
(O3)is added or some other disinfection method is used to kill any bacteria or microorganisims that may
be in the water.
Water is placed in a closed tank or reservoir in order for disinfection to take place.
The water then flows through pipes to homes and businesses in the community.
Complete the following flow chart by naming and describing the steps for purifying water.
1st:
2nd:
5th:
3rd:
4 th: