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Bacteriology Science Fair Project

Bacteria in Water Coolers

Bacteria in Water Coolers | Science Fair Projects | STEM Projects
Are you curious about the bacteria levels in water coolers and tap water? In this science project, you'll measure the size of bacteria growth in petri dishes filled with water from a water cooler and tap water.


The hypothesis is that the water from a water cooler will contain more bacteria than tap water.

Method & Materials

You will prepare two petri dishes, label them, and dampen two sterilized swabs with water from the water cooler and tap water. Then, you will rub the swabs across the agar in the petri dishes and close the covers. Finally, you will measure the size of the bacteria growth in the petri dishes for the next five days.
You will need two agar petri dishes, two disinfected swabs, one bottle of disinfected water, tap water, one water dispenser and water cooler, and one marker pen.


The results showed that tap water had smaller amounts of bacteria compared to water from the water cooler. The hypothesis was proven correct - the water from a water cooler does contain more bacteria than tap water.

Why do this project?

This science project is interesting because it shows how bacteria can grow quickly in places with high levels of moisture, and how chlorine is added to tap water to kill bacteria and prevent water-borne diseases.

Also Consider

Variations of this science project could include repeating the experiment with water from different sources such as a water fountain or well, or repeating the experiment using water samples from different types of water filters.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related videos

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