Indian tradition holds that storing water in brass pitchers prevents disease. Scientists have discovered that there is some truth in the tradition. The researchers collected river water samples and found fecal bacterial counts as high as 1 million bacteria per milliliter. However, they could detect no bacteria in the water after it had been stored for two days in traditional brass pitchers. Bacterial levels in plastic or earthenware containers remained high over the same period. How can brass, which is an alloy of copper mixed with zinc, make water safer to drink?
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Verified step by step guidance

1. Understand that brass is an alloy composed mainly of copper and zinc, both of which have antimicrobial properties. This means they can inhibit the growth or kill bacteria.
2. Recognize that when water is stored in brass pitchers, copper ions can leach into the water. These copper ions interact with bacterial cells, disrupting their cell membranes and interfering with essential cellular processes.
3. Consider the mechanism of copper's antimicrobial action: copper ions can generate reactive oxygen species and cause damage to bacterial DNA and proteins, leading to bacterial death.
4. Compare this to plastic or earthenware containers, which do not release antimicrobial ions, so bacteria can survive and multiply in water stored in these materials.
5. Conclude that the antimicrobial effect of copper in brass pitchers reduces or eliminates fecal bacteria in the water, making it safer to drink after storage.

Key Concepts

Antimicrobial Properties of Copper and Brass

Copper and its alloys, like brass, have natural antimicrobial effects that can kill or inhibit bacteria. Copper ions disrupt bacterial cell membranes, generate reactive oxygen species, and interfere with essential enzymes, leading to bacterial death. This explains why water stored in brass containers shows reduced bacterial counts.

Bacterial Contamination and Fecal Indicator Bacteria

Fecal bacteria, such as E. coli, indicate contamination by fecal matter and potential presence of pathogens. High bacterial counts in water suggest unsafe drinking conditions. Understanding these indicators helps assess water quality and the risk of waterborne diseases.

Material Influence on Microbial Survival in Water Storage

The type of container material affects bacterial survival in stored water. Non-antimicrobial materials like plastic or earthenware do not reduce bacterial levels, allowing microbes to persist. In contrast, antimicrobial materials like brass actively reduce microbial populations, improving water safety over time.