With dark red water coming out of Nam-gu, Pohang, Gyeongbuk, there have been more than 1,000 cases reported.

Pohang has reported that 925 complaints have been filed since the 10th, as a result of Pohang's report of residents in areas with black and red tap water.

Reported in other Nam-gu areas, mainly Daegu-dong, Donghae-myeon, and Daejam-dong, mainly in Ocheon-eup, Nam-gu.

Most of them are watershed areas of Yugang water purification plant.

Residents reported that the filter installed in the faucet or shower had turned black in a few days or had been wet with a wet tissue for a few minutes, resulting in stains and debris.

However, the number of reports, which reached 300 a day, has gradually decreased to show less than 100 a day.

Pohang City said 111 cases of tap water in the civil service area were inspected by an accredited water quality inspection agency such as the Gyeongbuk Institute for Health and Environment, and all of them appeared to meet the water quality standards.

In addition, as a result of the recent tap water filtration experiment in 47 rivers, it was found that there were 30 grades of 1st grade, 8 grades of 2 grades and 9 grades of 3 grades.

Nine 3 grades are 8 Principles of Ocheon-eup and 1 Daesang-dong.

Membrane filtration experiment is to check the degree of change in color by filtering 1ℓ of tap water and 0.45㎛ filter paper.

Grade 1 is excellent, grade 2 is good, and grade 3 is a level that shows discoloration in a short time.

The city and the civilian investigation team recently conducted a tap water filtration experiment, noting that the cause of discoloration is likely to be manganese, and decided to continue removing manganese deposited in the pipeline.