Elon Musk’s Moon‑City Dream Hits a Dry Patch: How Long Would Water Last?

Earlier this year Elon Musk announced that SpaceX intends to grow a fully self‑sustaining city on the Moon in less than ten years. The idea sounds straight out of a sci‑fi novel – domes, greenhouses, showers, and even a lunar café. Yet the whole concept hinges on a single, unforgiving resource: water.

Scientists have been hunting for lunar ice for decades, and recent missions have finally confirmed that sizeable pockets of frozen water hide in the permanently shadowed craters near the Moon’s poles. Estimates vary, but the most generous calculations put the total amount at roughly 1.3 trillion pounds – that’s about 600 million metric tons of ice.

In a paper published in Frontiers in Space Technologies, a team of planetary scientists ran the numbers for a city of one million residents. Using the upper‑limit water figure, they found that the settlement would gobble up all the accessible ice in just a little over two years. If the true amount turns out to be 20‑30 times lower, as many researchers suspect, the timeline shrinks dramatically.

The authors also modeled what would happen if the colony employed the International Space Station’s water‑recycling system, which boasts a 98 % efficiency. Even with that near‑perfect loop, the water would still run dry after about 110 years – a blink of an eye on a planetary‑scale timeline.

So what does this mean for Musk’s “self‑growing” vision? The study suggests that a sprawling megacity is probably out of reach with the Moon’s current water budget. Smaller habitats, however, look more feasible. A settlement housing a few thousand people could, in theory, live off the ice for several centuries, provided they recycle aggressively and keep water usage modest.

There are a few possible ways to stretch the water supply further. Improved recycling technologies, stricter water‑saving protocols, importing ice from near‑Earth asteroids, or—optimistically—discovering larger hidden reservoirs could all buy extra time. As co‑author Martin Elvis (Smithsonian Astrophysical Observatory) notes, “If the ambitious plans of the space billionaires are to be realized, then finding more water will be the first step.”

In short, the Moon may still become a stepping‑stone for humanity, but the idea of a bustling lunar metropolis with a million souls will have to wait until we either learn to live on a much smaller scale or find a way to bring a lot more water with us.