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Tokyo’s groundwater levels began recovering after pumping restrictions took effect, but the land that sank has not risen back to its former height. The sinking was caused mainly by heavy groundwater extraction, which compacted soft clay beneath the city. Tokyo’s Construction Bureau reports about 4.5 meters of cumulative subsidence at Minamisuna 2-chome in Koto Ward—more than “nearly 10 feet,” a figure the official sources cited here do not establish as the city’s precise maximum.
Why did Tokyo sink?
For decades, factories and a growing population relied heavily on groundwater. Pumping lowered water levels in underground sand aquifers. Water then drained from nearby, less-permeable clay layers; as the water pressure fell, clay particles compressed and the ground above them subsided. Tokyo’s Environment Bureau describes this process as a consequence of groundwater extraction, not the city simply settling as buildings were added.
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Subsidence was identified in Koto Ward in the 1910s. Reduced industrial groundwater use during World War II temporarily halted it, but renewed postwar demand brought the problem back in the 1950s. The low-lying eastern wards were especially affected.
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Tokyo’s Construction Bureau reports about 4.5 meters of cumulative subsidence at Minamisuna 2-chome in Koto Ward. This is a local figure, not a claim that every part of Tokyo sank by that amount. It also does not support “nearly 10 feet” as the city’s definitive maximum; the official local figure cited here is greater.
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Historical measurements show the severity of the crisis at its peak. The Institute for Global Environmental Strategies (IGES) reports that in 1965 Tokyo’s water table reached 58 meters below sea level, and that peak pumping reached nearly 1.5 million cubic meters per day in 1970. In some places, the peak subsidence rate was about 24 centimeters per year in 1968. These are historical measurements, not current readings.
What changed, and when did groundwater start recovering?
Tokyo and national authorities introduced pumping controls in the 1960s. IGES reports that groundwater levels began rising in the early 1970s as restrictions took effect, and the Tokyo Construction Bureau records a sharp decline in subsidence from around 1973. JICA’s staged history describes continued groundwater recovery and the cessation of subsidence from 1975 onward.
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The older IGES article also reported that pumping had fallen to up to 550,000 cubic meters per day in 2003 and that the water table had risen to 6–10 meters below sea level by its reporting period. Those figures describe that article’s historical reporting, not a verified 2026 groundwater level or pumping rate.
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No. Groundwater level and ground-surface elevation are different measurements. Pumping controls can let groundwater levels recover and help stabilize the ground, but once clay layers have compressed substantially, the lost ground height does not return. Japan’s Ministry of the Environment states: “Once subsided, the ground does not return to its original level.”
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Tokyo’s Environment Bureau likewise explains that ground that has subsided significantly does not return to its original height. “Rising again” is therefore misleading if it suggests the subsided land is being restored: it is the groundwater level that recovers, while the ground remains lower.
What do recent figures say—and what don’t they show?
The Ministry of the Environment’s FY2024 information for southern Kanto says no area has recorded annual subsidence of 2 centimeters or more since 1995. Its usage breakdown lists drinking water and public supply at 57.7% of pumping use in that regional accounting. These figures describe southern Kanto, not Tokyo alone, and the regional indicator is not a direct measurement of Tokyo’s groundwater level.
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Tokyo’s groundwater also does not behave like one uniform reservoir. The Environment Bureau describes different flow tendencies at shallow and deep levels, and longer groundwater residence times in lowland areas than on uplands. The figures cited here do not establish a single refill rate for the city.
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IGES noted that buildings and pavement covered more than 80% of the ward-area surface at the time of its reporting, limiting rainwater infiltration. It described conserving green areas and farmland and using infiltration facilities as ways to support groundwater recharge. These are planning measures that may support recharge; they do not undo the compaction that caused historical subsidence or imply that household-scale measures can reverse it.
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