Scientists Think Humans Could Live on the Moon, but Water Could Limit Lunar Cities

The idea of humans living permanently on the Moon is moving from science fiction toward an engineering and resource-management question. NASA and its commercial partners are developing technologies for longer lunar missions, while scientists continue to study whether the Moon has enough usable resources to support people for decades or even centuries.

A new study published in Frontiers in Space Technologies has highlighted one particularly important limitation: water.

Researchers Martin Elvis and Jonathan McDowell examined whether lunar water resources could support large permanent settlements. Their conclusion is striking: even a generous assumption of 1 billion tons of lunar water would not be enough to sustain a city of one million people indefinitely, even with highly efficient recycling.

That does not mean humans cannot live on the Moon. Instead, it suggests that the scale of future settlements could be constrained by one of the most basic requirements for life.

Why Water Matters So Much on the Moon

Water on the Moon would be far more valuable than simply providing drinking supplies.

A lunar settlement would need water for drinking, food production, hygiene and sanitation. Water can also be separated into hydrogen and oxygen through electrolysis, potentially providing ingredients for rocket propellant.

The Moon does contain water ice, particularly in permanently shadowed regions near the poles. These extremely cold crater floors can preserve ice because they receive little or no direct sunlight.

The new study notes that lunar missions have identified potentially large quantities of water, with some estimates reaching around 1 billion tons. But determining exactly how much water exists—and how accessible it is—is still a major challenge.

This distinction is crucial. Finding evidence of ice is not the same as having an easily accessible underground reservoir that a settlement can continuously extract.

A Million-Person Moon City Could Run Out of Water

The researchers modelled lunar settlements of different sizes to estimate how long their water resources could last.

Under an extremely optimistic scenario involving 1 billion tons of water and 98% recycling efficiency, comparable to the water-recycling performance cited for the International Space Station, a settlement of one million people would exhaust its water supply in a little more than a century.

Without recycling, the available water would last only a few years at that population scale.

The situation becomes even more challenging because the study says current best estimates of lunar water could be roughly 30 times lower than the generous 1-billion-ton assumption.

That would dramatically reduce the amount of time a large settlement could remain self-sufficient.

The result is not a prediction that a million-person lunar city will never exist. Rather, it shows that such a settlement would require either significantly more water, much better recycling, lower consumption or a combination of all three.

Smaller Moon Settlements Look More Realistic

Population size changes the calculation dramatically.

According to the study, a lunar village of around 1,000 people, or even a town of roughly 10,000, could potentially remain sustainable for centuries under the assumptions examined.

That creates an important distinction between a Moon base and a Moon city.

A small scientific or industrial settlement could potentially operate with carefully controlled resource consumption. A city with hundreds of thousands or millions of residents would require a much larger and more reliable resource base.

In other words, the first permanent lunar communities may look more like remote research stations or industrial towns than Earth-style megacities.

Power May Not Be the Biggest Problem

One of the more surprising findings from the study is that electricity may not be the fundamental limitation.

Some areas around lunar polar craters receive sunlight for very long periods. The study argues that large solar installations could potentially generate substantial amounts of electricity, including a theoretical scenario involving around 3 gigawatts from tall photovoltaic structures positioned near well-lit crater rims.

The Moon also contains silicon and other materials that could eventually become useful for manufacturing.

That opens up an entirely different possibility: lunar infrastructure could eventually produce some of the materials and energy needed for an expanding space economy.

But electricity cannot replace water. Solar panels can generate power, while water must either be found, recycled or transported from somewhere else.

NASA Is Already Preparing for Long-Term Lunar Operations

The water problem comes as NASA is developing plans for a sustained human presence on the Moon.

NASA's current Moon Base strategy focuses on the lunar South Pole, where access to resources and favorable lighting conditions could support longer-term operations. The agency says the approach will develop lunar capabilities in phases rather than attempting to build a complete settlement immediately.

NASA is also funding missions designed to better understand the lunar environment and resources. In March 2026, for example, NASA selected Intuitive Machines for a lunar delivery mission carrying science and technology payloads intended to improve understanding of lunar regolith and the radiation environment around the South Pole.

This resource mapping will be important because future lunar settlements will depend heavily on knowing where usable materials are located.

Water Is Not the Only Challenge

Although the new study focuses on water, a permanent human settlement would face several other difficult problems.

The Moon has no Earth-like atmosphere and is exposed to radiation and extreme environmental conditions. Lunar dust is another major concern.

NASA describes lunar regolith as sharp, abrasive and electrostatically charged. The particles can cling to spacesuits and equipment, enter seals and mechanisms, and potentially create health problems if they enter habitats and are inhaled.

NASA is actively testing technologies to mitigate this problem. In August 2026, the agency reported ongoing work at its Lunar Development and Test Facility to understand and reduce the effects of lunar dust on equipment and astronauts.

There are also major questions surrounding long-term human health in the Moon's low-gravity environment, habitat construction, food production, transportation and reliable life-support systems.

So water should not be viewed as the only obstacle to lunar habitation. The new research identifies it as a particularly important constraint when considering very large, self-sustaining populations.

How Could Scientists Solve the Water Problem?

The researchers identify several possible paths.

One is to develop water-recycling systems that are substantially more efficient than today's systems. Another is to reduce consumption through technologies such as highly efficient agriculture.

A third possibility is importing water from other space resources, potentially including asteroids.

The most straightforward possibility may ultimately be finding more lunar water.

Current surveys do not fully reveal what lies beneath the lunar surface. The study notes that existing techniques generally investigate only relatively shallow depths, while lunar regolith can extend much deeper. More extensive exploration could therefore change estimates of how much water is actually recoverable.

That means today's estimates should not be treated as the final word on the Moon's water inventory.

What This Means for the Future of Lunar Settlements

The new research does not eliminate the possibility of people living on the Moon.

Instead, it changes the scale of the question.

A small lunar settlement appears considerably more plausible than a massive city under current resource assumptions. Early bases could focus on science, resource extraction, manufacturing and technology development while gradually improving recycling and resource-utilization systems.

If scientists discover substantially more water beneath the surface, or if future technology dramatically reduces water consumption, the long-term picture could change.

For now, however, the research highlights a basic reality: building homes on the Moon may be an engineering challenge, but keeping a large population supplied with water could be the harder sustainability problem.

Conclusion

Humans may eventually live on the Moon, but creating a large, self-sustaining lunar city is a much bigger challenge than simply reaching the lunar surface. A September 2026 study found that even a generous estimate of one billion tons of lunar water would not sustainably support a one-million-person city for more than about a century under highly efficient recycling assumptions.

The next major breakthrough may therefore come not from building bigger habitats, but from finding more accessible lunar water and developing far more efficient ways to recycle and use it.

As NASA and commercial space companies expand lunar exploration, resource mapping, water extraction and life-support technology will be among the developments worth watching closely.

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This article is for informational and educational purposes only and should not be considered investment advice.