Lunar water reserves may limit future moon cities

Researchers have released a study in the journal ‘Frontiers in Space Technologies’ suggesting that the ambitious plans for large-scale lunar cities may be limited by available water resources. Scientists Martin Elvis and Jonathan McDowell analyzed the feasibility of sustaining large populations on the Moon, focusing on the water ice found in permanently shadowed craters at the lunar poles.

Even under highly optimistic assumptions—including a massive reserve of 1 billion tons of water and a 98% recycling efficiency similar to the International Space Station—a city of one million inhabitants would likely exhaust its water supply in approximately 100 to 120 years. The primary driver of consumption is estimated to be agriculture, which requires significantly more water than individual human needs.

If water reserves are closer to more conservative estimates, which are up to 30 times lower than the optimistic scenario, a million-person city could run out of water in just a few years. While smaller settlements of a few thousand people could potentially survive for centuries, the study suggests there are physical limits to how large a lunar society can become.