45% of people in Ghana, Niger and Nigeria live in areas of high water risk, study finds

A growing water crisis is unfolding across West Africa, putting millions of lives at risk, according to a new study by WaterAid and Tree Aid.

The report, From Roots to Rivers: How Deforestation Impacts Freshwater Access , finds that 45 per cent of people — more than 122 million across Ghana, Niger and Nigeria — are now exposed to unsafe drinking water, an increase of 20 million in just five years. The study links this alarming trend directly to deforestation and the loss of vegetation cover that sustains freshwater systems.

Forests and vegetation, the report explains, play a crucial role in protecting freshwater resources by stabilising soils, filtering pollutants and regulating rainfall. Their destruction is disrupting these natural processes and threatening the reliability of water supplies used for drinking, food production and health.

Drawing on 12 years of Earth Observation data from satellites between 2013 and 2025, the study examined vegetation, rainfall and water coverage across the three countries — chosen for their diverse ecological and climatic conditions within West Africa. For the first time, the analysis provides clear evidence of a correlation between deforestation and freshwater decline.

In Niger and Nigeria, every 1,000 hectares of forest loss corresponds to an average of 9.25 hectares of surface water loss. In Nigeria, the figure stands at 6.9 hectares, while in Niger it rises to 11.6 hectares. In Ghana, meanwhile, forest loss is closely associated with the deterioration of surface water quality rather than quantity.

Reduced access to clean, safe water due to ongoing deforestation is further compounded by climate change, the study warns. Intense rainfall, without vegetation to filter it or stabilise soil, leads to sediment and pollutants entering rivers, lakes and reservoirs. Over time, this not only reduces available drinking water through diminished groundwater absorption and evapotranspiration, but also lowers the quality of what remains.

The scale of the problem is most severe in Niger, where 99.5 per cent of available surface freshwater is now considered at risk of sedimentation and poor quality. In Nigeria, around 85.6 million people live in areas highly vulnerable to surface water loss from deforestation. 

In Ghana, contamination remains the central concern, with forest loss directly linked to worsening surface water quality. Between 2013 and 2025, the country lost around 298,000 hectares of vegetation, which is roughly equivalent to losing an area the size of Edinburgh each year. Nigeria recorded vegetation loss of 324,000 hectares, comparable to an area the size of Birmingham annually. 

Niger, however, showed modest improvement, managing to increase its vegetation cover by 101,000 hectares.

The study underscored that water security in West Africa cannot be separated from forest management. WaterAid and Tree Aid are calling on policymakers to integrate forest and water priorities into climate plans, financing frameworks and adaptation strategies, particularly through investment in strengthened, climate-resilient and equitable water services that prioritise vulnerable communities and promote universal access to safe water.