(CNN) New satellite images show just how far Cape Town's biggest water reservoir has shrunk as the city nears the day when it completely runs out of water.

Drought, population growth and climate change are helping fuel Cape Town's water crisis . Officials believe taps will run dry on April 12, cutting off water access to the city's 4 million residents.

Satellite images provided to CNN by planet.com show the Theewaterskloof Dam, Cape Town's largest water reservoir, at dangerously low levels. It's only 13 percent full this week — down a full percent from last week.

The dam is so massive, it holds more than 480,000 megalitres of water, or 126 billion gallons. It accounts for 53 percent of all water in the region's dam system.

The broader impact

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