The geology of Lusaka is divided between uneven-depth folded and faulted schist in the north, and limestone with dolomitic marble in the south, to a depth of . These rocks yield more groundwater than the crystalline basement rock which is the most prevalent in Zambia. The limestone regions have formed underground karsts, into which surface water drains, causing a lack of major rivers and few streams. The city lies on a drainage divide, with waters in the north east of the city draining into the Chongwe River, via the Ngwerere and Chalimbana streams, while the west and south are within the basin of the Kafue River. Both the Chongwe and the Kafue ultimately drain into the Zambezi River. The soil is predominantly Leptosols in the schist region and Phaeozems on the dolomite. These non-clay soils result in reduced filtration of groundwater before it reaches aquifers.