From Halopedia, the Halo wiki
The GWC Trans-African Pipelines, built by the Global Water Campaign, are located alongside the Tsavo Highway in Africa on Earth. Using the road as a route through which it carries melt water from GWC purification plants in the jungles near Mount Kilimanjaro, the pipes then transport the water along the Tsavo Highway across the rest of the African continent for distribution. There are several pump houses along the way, including Voi Municipal Water Pump House 03 which supplied water to the town of Voi.
Pump house 03 near Voi.