Permeable Paving Blocks in Seoul Fail to Drain Water Despite 'Sponge-like' Design

On a rainy city street, water pools on the asphalt, while the sidewalk paved with blocks remains clear.

This is where permeable blocks, designed to allow water to pass through, have been installed.

The blocks are engineered with numerous microscopic pores that allow rainwater to drain through and seep into the soil.

[Cho Si-hyung / Seoul City Permeable Block Manager: Permeable blocks absorb some of the rainwater, playing a role in preventing urban flooding.]

Videos from manufacturers show a stark contrast between permeable blocks that absorb water and regular sidewalk blocks that do not.

But do the permeable blocks installed on actual streets drain water as effectively?

The Seoul Institute conducted a field survey of 30 locations where these blocks had been installed for less than a year.

The testing method involved placing a bucket on the blocks and measuring how quickly the water drained through.

While 10 locations met the installation standard of absorbing at least 0.1mm of water per second, 18 locations showed an absorption rate of only 40 percent of the standard, and the remaining two did not drain any water at all.

This means two-thirds of the locations were defective.

[Park Dae-keun / Senior Research Fellow, The Seoul Institute: The results showed that about two-thirds were either clogged or mostly blocked. We need to recognize the severity of these findings.]

In 2015, the Seoul Metropolitan Government enacted an ordinance making the installation of permeable blocks mandatory to reduce rain-related damage.

The city explains that over time, foreign substances such as dust and dirt can enter and clog the pores of the blocks.

However, as a large number of blocks installed less than a year ago were found to be defective, critics point out that it is necessary to investigate whether substandard products were supplied in the first place.

The Seoul Metropolitan Government has decided to expand the scope of its investigation to 1,000 locations for precise measurement.

[Exclusive] Rainy Season Begins, But 'Permeable Blocks' Fail to Function (July 7, 2026, Morning Wide)

Reported by Jang Se-man | Written by Lee Se-young | Video by Kim Young-hwan | Video Editing by Ahn Yeo-jin | Produced by SBS Digital News
※ Please note: This article was translated by AI and may contain errors.