Southwestern Kenya provides water for some 10 million Kenyans, but illegal settlement and deforestation have destroyed at least 25 per cent of the regions vegetation over the last 20 years.

Security officers have been combing through Kenya's most important forest to make sure thousands of people have obeyed an order to gather their belongings and vacate the area.

The government is ordering up to 30,000 families to leave their homes - saying that a clear out is necessary to protect the Mau forest and ensure that water keeps flowing.

What happens to the Mau, which feeds Lake Victoria and the White Nile, has big implications for a region where 23 million people are afflicted by a fifth year of drought.

The closed-canopy forest is the largest ecosystem of its kind in Kenya and high rainfall makes it the single most important source of water for more than 10 million people not just in Kenya but throughout the region.

The Mau feeds nine main rivers, four of which drain into Lake Victoria, a source for the Nile, the worlds longest river.

However, in the past 20 years thousands of hectares of forest, or 25 per cent have been lost because of human activity such as illegal logging and farming.

The Kenya Forest Service has also sent more rangers to Mau so that families who leave the country's largest source of water do not return.

Al Jazeera's Ama Boateng met some of those now being evicted.