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Aging sewer system behind sinkholes? 1 in 3 Seoul pipes over 50 years old, data finds.

Published: 15 Apr. 2025, 09:49

A sinkhole in Gangdong District, eastern Seoul, on March 24 [NEWS1]

Nearly one in three pipes in Seoul sewers are over 50 years old and have become "super-aged," data revealed Tuesday as a major cause of a series of sinkholes in central Seoul.

As of December 2023, 3,300 kilometers (2,051 miles), or 30.4 percent of Seoul’s total 10,866 kilometers of sewer pipelines, were more than 50 years old, according to data submitted by Democratic Party lawmaker Jin Sun-mee.

Pipelines older than 30 years totaled 6,028 kilometers, accounting for 55.5 percent of the entire network. In general, pipes that are more than 30 years old are classified as aging infrastructure.

In particular, the proportion of pipes older than 50 years exceeded 40 percent in districts such as Jongno in central Seoul, Yongsan in central Seoul, Seongbuk in northern Seoul and Yeongdeungpo in western Seoul.

Jongno District had the highest share, with 53.5 percent of its pipes exceeding 50 years. Yongsan followed at 48.5 percent, then Seongbuk at 47.7 percent, Yeongdeungpo at 45.7 percent, Mapo in western Seoul at 45.4 percent, Guro in western Seoul at 43.5 percent and Seongdong in eastern Seoul at 42.2 percent.

The percentage of pipes over 30 years was also high: 66.3 percent in Jongno, 66.2 percent in Dobong in northern Seoul, 65.2 percent in Yongsan, 63.6 percent in Yeongdeungpo and 63.2 percent in Seocho in southern Seoul.

A sinkhole in Busan on April 14 [JOONGANG ILBO]

Aging sewer lines are cited as a primary cause of sinkholes. Water leaking through cracks and holes in the pipes can wash away the soil underground, creating empty voids that eventually cause the surface to collapse.

According to the Ministry of Land, Infrastructure and Transport, sewer pipe damage was the leading cause in 394 of the 867 ground subsidence incidents recorded nationwide over the past five years from 2020 to 2024. That accounts for 45.4 percent of all cases.

Seoul city spends around 200 billion won each year to repair approximately 100 kilometers of aging sewer lines, but that pace has not been enough to keep up with the rate of deterioration. The high cost of large-scale replacement is also a major challenge.

“To respond adequately to aging infrastructure, we need to repair about 150 kilometers annually," said a city official. "We are working to secure additional funding. We have requested financial support from the central government and are currently in talks.”

“We cannot leave the safety of the roads that citizens use every day to chance,” said lawmaker Jin, urging the government and local authorities to “disclose safety-related information transparently and swiftly implement preventive measures, including large-scale sewer line repairs.”

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.

BY KIM EUN-BIN [[email protected]]