Comparison of Efficacy of Portable Filtration Straws in Eliminating E. coli Contamination

Overview

Backpacking often presents the challenge of finding safe drinking water. While some purification methods, such as iodine tablets, can be harmful with frequent use, hikers may rely on filtration straws to treat water from natural sources like creeks and rivers. In this experiment, I tested which filtration straw was most effective at removing bacteria, including E. coli. I collected creek water and prepared a separate E. coli sample, then filtered both through different straws. The filtrates were used to inoculate 30 nutrient agar plates, which were incubated to observe bacterial growth. Results showed that all straws except one (Modern Needs) effectively removed bacteria from creek water. However, in the E. coli trials, only the Lormandy Survival Straw produced completely sterile plates. The high concentration of E. coli appeared to overwhelm most filters. Overall, the Lormandy straw proved to be the most reliable and effective option.

Competition history

• CSEF 2026 Product Science (Junior Division) · Entry J-19-13

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