Dare to Share Your Water: A Study of Bacteria in Backwash

Overview

Objectives/Goals To determine if drinking a water bottle after excercise with either a straw or by mouth will contaminate the remaining water in the bottle with bacteria from the mouth. Methods/Materials After one hour of excercise, I asked 15 subjects to drink from a water bottle, once by mouth and once by straw. The subjects were asked to drink 3/4 of the water in the bottle. A one milliliter sample of the remaining water was removed and poured into the culture medium. After 48 hours at room temperature, the colonies were counted. A control was taken. Materials: Petri dishes Culture medium Calibrated dropper Straws 0.5 liter arrowhead water bottles gloves and mask marker magnifying glass Results 100% of the 30 samples (15 by mouth and 15 by straw) grew bacterial colonies on the culture plates. The drinking by mouth method contaminated the water bottles more than the drinking by straw method. Conclusions/Discussion I concluded that drinking water by mouth or by straw will contaminate the remaining water in the bottle. My experiment suggests that the way you drink the water will effect the amount of bacteria that is backwashed. Sharing other people's water, after sporting events, will expose you to illnesses from their backwashed bacteria and viruses.

Competition history

• CSEF 2005 Microbiology · Entry J1302

Resources

• CSEF project summary ↗

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