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The Gongchon Water Purification Plant in Incheon, where the larvae were discovered, introduced an advanced water treatment process after the red tap water crisis last year. This is the process of collecting water, filtering and disinfecting, and adding one to the process that was sent to each house. Immediately before disinfection, water is passed once more to activated carbon such as charcoal to catch odor or foreign substances. However, larvae were immediately identified from the newly added activated carbon.

Reporter Kang Min-woo heard an expert's talk about how he could do it in the most clean and strictest way.

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The granular activated carbon filter paper of the Gongchon Water Purification Plant where larvae were found is simply a filter made of charcoal powder.

At this time, it is highly likely that the midget adult lays eggs on the activated carbon filter and the eggs that have passed through the filter have hatched into eggs or larvae and flowed to the home.

Experts estimate that there was a loophole in management and operation.

The filter is inside the facility, but it is not completely blocked from the outside, so insects can enter when the facility door is opened or closed.

In order to manage the water treatment plant, lighting is often turned on at night, but insects may fly in.

[Dok Go-suk/Dept. of Civil and Environmental Engineering, Dankook University: It is a bush area. Since it is an area with no lights, of course these things can go inside (by looking at the light). In order to monitor by CCTV, I installed (lighting) on ​​it... .]

Some experts point out filter cleaning problems.

The cleaning cycle of granular activated carbon filters in Gongchon Water Purification Plant in Incheon is 10 to 20 days, which is longer than other water purification plants that are 3 to 4 days, which may have created an environment where larvae live.

[Bae Jae-geun/Professor, Department of Environmental Engineering, Seoul National University of Science and Technology: (Filter) If foreign matters are accumulated, foreign matters will accumulate and they will rot after time. In the meantime, some caterpillars can inhabit there.] The

joint research team will open up a number of possibilities, and will investigate the occurrence of tap larvae and their influx into the home through detailed investigations of the Gongchon and Bupyeong plants.

(Video Editing: Wonhee H., CG: Lee Yoojin)  

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