No Bacteria Detected in Arisu After 24 Hours of Repeated Drinking from a Tumbler

Investigation of Changes in Arisu with Repeated Consumption and Long-Term Storage

Residual Chlorine Proven Effective in Suppressing Microbial Growth in Water

No general bacteria were detected for 24 hours even after repeatedly drinking Arisu from a tumbler. The residual chlorine (0.2 mg/L) maintained during the tap water supply process killed general bacteria introduced from outside within one hour and inhibited bacterial growth.

On May 14, the Seoul Metropolitan Government announced the results of an investigation into microbial changes resulting from repeated drinking and prolonged storage of Arisu. The results showed that the residual chlorine suppressed the growth of general bacteria that could enter from external sources.

This investigation was conducted by repeatedly drinking Arisu stored in a tumbler and analyzing the microbial changes over time. The Seoul Water Institute focused on determining whether general bacteria would proliferate with repeated drinking and over time. Nine participants repeatedly drank water from a tumbler, and samples were collected to analyze changes in general bacteria at 1 and 3 hours after the first drink, and at 5, 7, and 24 hours after the second drink.

Although residual chlorine is known to be responsible for the characteristic odor of tap water, it serves to inhibit the growth of microorganisms in the water, thereby ensuring sanitary safety. It has been found to help suppress the proliferation of general bacteria in environments where water is frequently shared, especially in the summer.

To more broadly examine the impact of repeated drinking on microbial changes, the Seoul Water Institute also analyzed two types of commercial bottled spring water without residual chlorine under the same conditions. As a result, an average of 41 CFU/mL of general bacteria was detected after the first drink and an average of 85 CFU/mL after the second drink. In some cases, the bacterial count increased up to 60 times within three hours, indicating that caution is needed when sharing bottled water over an extended period. Since the sanitary condition of bottled water can vary depending on how it is consumed and stored after opening, it is advisable to drink it as soon as possible.

In addition to the microbial analysis, the contents of key minerals such as calcium, magnesium, potassium, and sodium were also examined. Arisu was found to contain 42 mg of minerals per liter. In comparison, the average content of key minerals in five types of domestic commercial bottled spring water examined in this study was 29.8 mg/L.

Meanwhile, the Seoul Water Institute explained that, since microorganisms can proliferate with repeated drinking and prolonged storage during the summer, using tap water containing residual chlorine in a tumbler can help with sanitary management. The institute also added that if the odor of tap water is unpleasant, pouring it into a clean container and refrigerating it can help reduce the smell.

Yoon Hee-cheon, Director of the Seoul Water Institute, stated, "Arisu is drinking water whose safety has been verified through rigorous water quality testing on 362 items. Since microbial proliferation is effectively suppressed even when water is shared over a long period in the summer, drinking it from a tumbler can promote healthy and hygienic water consumption in summer and help reduce single-use product waste."

This content was produced with the assistance of AI translation services.