Lunar Water Reserves May Sustain Only Small Towns for Centuries
New research indicates that a million-person moon city would exhaust available water within a century, even with aggressive recycling.
By Lorenzo Evans ·
The water supply on the moon may be too limited to support large-scale urban development for long periods, according to a new study published in Frontiers in Space Technologies. Researchers from Harvard University and Durham University analyzed the planet's resources and found that while power generation is feasible, water availability poses a strict constraint on population size and longevity.
The study responds to public claims by major space industry leaders. In February 2026, SpaceX CEO Elon Musk stated on social media that the company was prioritizing a self-growing lunar city over Mars settlement, projecting a timeline of under 10 years. Blue Origin CEO Jeff Bezos has separately claimed that millions of people will live in space by 2045. Martin Elvis, a senior astrophysicist at Harvard's Smithsonian Astrophysical Observatory, and Jonathan McDowell, an honorary professor at Durham University's Space Research Centre, decided to test these ambitions against current data.
The analysis focused on two essential resources: power and water. The researchers determined that solar and nuclear energy sources are sufficient to support one million people on the lunar surface. Water, however, presents a tighter limit. Current estimates suggest approximately one billion tonnes of water exist in permanently shadowed polar regions. Under the assumption that 98 percent of this water is recycled, a rate comparable to the International Space Station, a population of one million would deplete this reserve in about 100 years.
Elvis noted that the total volume sounds large but is modest in practical terms. He compared the supply to an aquarium the size of Central Park filled until the Statue of Liberty is just submerged. He described it as a small lake that cannot supply a big city for very long. A smaller settlement of 10,000 people would be sustainable for centuries under the same assumptions. McDowell stated that covering the moon with cities requires finding a way to bring water there because it is not currently available in sufficient quantities.
The researchers believe their assumptions may be optimistic. Elvis suggested that the estimate of one billion tonnes is likely 20 or 30 times too high. He further estimated that only one-third to one-half of the present water would be recoverable. His best guess is that the usable amount is about one percent of the original figure, which would reduce the lifespan of a million-person city from 100 years to one.
Uncertainty also exists regarding the physical form of the lunar water. Gordon Osinski, a professor of planetary geology at Western University in London, Ontario, said satellite measurements carry uncertainties. He believes the water is present but requires on-the-ground confirmation. He suggested it may resemble Arctic permafrost, consisting of sub-millimetre ice crystals mixed into soil that are difficult to extract. McDowell said the findings should not discourage exploration, noting that the truth is never negative and that trying is preferable to attempting projects that will not work.
