▲ Recovery training simulating flood damage as part of the Safe Korea Exercise
With the monsoon season in full swing, flooded roads have become a common sight.
Many people often assume that it is safe to walk through water that is only ankle-deep.
However, in rapidly flowing water, even shallow depths can cause a person to lose their footing, and hazards such as displaced manhole covers can lead to serious accidents.
If a road is flooded due to heavy rain, it is safest to avoid it altogether.
Walking through floodwater carries risks such as falling into an open manhole, being swept away by sudden currents, stepping on dangerous objects like glass, or suffering an electric shock.
According to the U.S. National Weather Service (NWS), just 15 cm (about 6 inches) of fast-moving floodwater is enough to knock an adult off their feet.
This depth corresponds to the area between the ankle and the lower calf for an average adult.
Manholes also require caution.
During heavy downpours, the pressure of rapidly rushing rainwater can often cause manhole covers to pop up or be displaced from their frames.
A 2014 experiment by the National Disaster Management Research Institute showed that if 50 mm of rain per hour falls in the Gangnam Station area of Seoul, a 40 kg iron manhole cover can be ejected about 27 cm into the air in just 41 seconds, shooting out a water column 50 cm high.
During the 2022 heavy rains in the Seoul metropolitan area, a brother and sister died after falling into an open manhole while moving after getting out of their car.
Last year, a woman in her 30s also fell into a manhole that had been displaced by heavy rain in Busan.
According to a 2022 report by the Seoul Institute of Technology, titled "Derivation of Design Standards for Installing Fall Prevention Facilities in Sewer Manholes," there were a total of 113 incidents of sewer manhole covers opening in Seoul between 2018 and 2022.
Of these, 110 incidents occurred in 2022 alone, when record-breaking rainfall hit the region.
The report attributed the increase in manhole cover displacement to abnormal weather patterns, such as the increased frequency and intensity of heavy rain caused by climate change, and the exceeding of sewer capacity due to concentrated rainfall over short periods.
When in an underground space, one should evacuate immediately if even a small amount of water begins to rise or if water starts backing up from drains.
Water flowing down underground stairs is only navigable up to shin-depth (40 cm); once it reaches knee-depth, movement becomes difficult.
Since it is difficult to open an exit door alone when water reaches knee-height, the power should be cut off, and multiple people should work together to force the door open.
Attempting to retrieve a vehicle from a flooded underground parking lot is also dangerous.
In 2022, seven people died and two were injured while trying to move their cars from an apartment basement in Pohang, North Gyeongsang Province, which had flooded due to Typhoon Hinnamnor.
The Ministry of the Interior and Safety advises that underground spaces can flood within 5 to 10 minutes once water begins to enter, and that people should not enter flooded underground parking lots to move vehicles.
In particular, once water begins to flow down a ramp, the pressure makes it impossible to move a vehicle, so people should evacuate immediately, leaving the car behind.
Even if you are inside a vehicle, driving through flooded roads is dangerous.
The U.S. National Weather Service warns that vehicles begin to lose traction in about 15 cm of water, most passenger cars can be swept away in about 30 cm, and 60 cm of rushing water can carry away even SUVs and pickup trucks.
According to the Korea Road Traffic Authority’s Traffic Accident Analysis System, there were 127 traffic accidents (1 death, 195 injuries) that occurred when road conditions were classified as "flooded" between 2021 and 2025.
The ratio of injuries to the number of flood-related accidents is 153.5%, which is 11.2 percentage points higher than the average injury ratio of 142.4% for all traffic accidents.
In its guidelines for flooded vehicles, the Ministry of the Interior and Safety advises drivers not to enter roads or underpasses where water is flowing in, and to abandon the vehicle and evacuate if they have already entered.
It also recommends moving the vehicle to a safe location before the water reaches two-thirds of the tires (about 40–45 cm) and, if flooded, using the metal rod of the headrest to break the window and escape.
If the car is flooded and the doors will not open and no other means are available, one should wait until the difference between the water level inside and outside the vehicle is 30 cm or less before opening the door to escape.
If the vehicle is already submerged, do not attempt to start the engine; instead, request towing and repairs.
Starting the engine while flooded can cause water to enter the engine, leading to further damage.
In urban areas with many paved surfaces like cement and asphalt that do not absorb rainwater, water can quickly rush into sewer pipes and catch basins, increasing the risk of flooding.
Furthermore, as the frequency and intensity of extreme urban rainfall increase due to climate change-induced abnormal weather, cities face simultaneous risks of river flooding and urban flooding where water cannot drain through sewer and drainage systems.
It is recommended to clear cigarette butts and trash from catch basins and remove covers installed to block odors or insects.
Clogged catch basins should be reported to the local city or county office.
Electric shock is another major type of accident that can occur during flooding.
During the heavy rains in the Seoul metropolitan area in July 2001, 19 people died from electric shocks caused by current leaking from streetlights and traffic signals on flooded roads.
In August 2022, a district office employee in his 60s in Dongjak-gu, Seoul, died from an electric shock due to a nearby power leak while clearing a fallen tree on a flooded road.
According to the Korea Electrical Safety Corporation’s "Electrical Disaster Statistical Analysis" (2025) report, there were 371 casualties (28 deaths, 343 injuries) from electric shock accidents in 2024.
By season, the summer months of June to August saw the highest number of casualties at 127 (34.2%), with August (47 casualties, 12.7%) being the peak month.
The corporation analyzed that electric shock accidents occur frequently in summer because high humidity and moisture make electrical leakage more likely, human body resistance decreases due to sweat, and longer daylight hours lead to longer working times.
It also added that wearing lighter clothing, which exposes more skin, and a lack of concentration due to the heat are contributing factors.
The corporation warns that because electric shock casualties are concentrated during the rainy season (June–September) when there is heavy rain and moisture, one should avoid approaching electrical facilities if roads are flooded.
If your home is flooded, electricity can flow through outlets into the standing water, so you must turn off the main power switch at the distribution board before pumping out the water.
Afterward, you should have a professional agency inspect the electrical system and confirm it is safe before using electricity again.
(Photo: Yonhap News)
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