The Water and Sanitation Program (WSP) has provided advice on investments and policies to its partners and clients in developing countries for more than 21 years. Much of its early work, such as that on low-cost technologies, demand-responsiveness, strategic sanitation planning, and participatory hygiene have now become standard approaches in the sector. Drawing from its field network in over 30 countries, the Program is continuing to explore new frontiers of knowledge. For example, it is identifying and testing private sector partnerships that provide services to the poor and helping its partners gain access to current sector practices. The Program has been a forerunner of a growing list of partnership programs managed by the World Bank. Its well-established global network, strong tradition of client responsiveness, and continuous open dialogue with World Bank clients in developing countries provide a model for development practice. The Program is focusing its attention and resources on the most critical countries and regions of its operation. It is building partnerships with a broader range of stakeholders and developing alliances with the leading international agencies and sources of knowledge in the sector. Limiting further overall growth, the Program's management is seeking to reduce fixed costs and increase flexibility to enable the WSP to reduce risk and better respond to opportunities and new client demands.

Weathered crystalline bedrock aquifers sustain water supplies across the tropics, including East Africa. Although well yields are commonly <1 L s⁻¹, more intensive abstraction occurs and provides vital urban and agricultural water supplies. The hydrogeological conditions that sustain such high abstraction from crystalline bedrock aquifers remain, however, poorly characterised. Five sites of intensive groundwater abstraction (multiple boreholes yielding several L s⁻¹ or more) were investigated in Uganda and Tanzania. Analysis of aquifer properties data indicates that the sites have transmissivities of 10–1,000 m² day⁻¹, which is higher than generally observed in deeply weathered crystalline bedrock aquifers. At four of the five sites, weathered bedrock (saprolite) is overlain by younger superficial sediments, which provide additional storage and raise the water table within the underlying aquifer. Residence-time indicators suggest that: (1) abstracted water derives, in part, from modern recharge (within the last 10–60 years); and (2) intensive abstraction is sustained by recharge occurring over several decades. This range of encountered residence times indicates a degree of resilience to contemporary climate variability (e.g. short-term droughts), although the long-term sustainability of intensive abstractions remains uncertain. Evidence from one site in Tanzania (Makutapora) highlights the value of multi-decadal groundwater-level records in establishing the long-term viability of intensive groundwater abstraction, and demonstrates the influence of intra-decadal climate variability in determining the magnitude and frequency of recharge.

The continuous abstraction of groundwater from Arusha aquifers in northern Tanzania has resulted in a decline in water levels and subsequent yield reduction in most production wells. The situation is threatening sustainability of the aquifers and concise knowledge on the existing groundwater challenge is of utmost importance. To gain such knowledge, stable isotopes of hydrogen and oxygen, and radiocarbon dating on dissolved inorganic carbon (DIC), were employed to establish groundwater mean residence time and recharge mechanism.¹⁴C activity of DIC was measured in groundwater samples and corrected using a δ¹³C mixing method prior to groundwater age dating. The results indicated that groundwater ranging from 1,400 years BP to modern is being abstracted from deeper aquifers that are under intensive development. This implies that the groundwater system is continuously depleted due to over-pumping, as most of the sampled wells and springs revealed recently recharged groundwater. High ¹⁴C activities observed in spring water (98.1 ± 7.9 pMC) correspond with modern groundwater in the study area. The presence of modern groundwater suggests that shallow aquifers are actively recharged and respond positively to seasonal variations.