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.

Safe drinking water for all is unlikely to be achieved without major improvements in the sustainability of rural water supplies in sub-Saharan Africa. Despite heavy dependence on groundwater across the African continent, there is little empirical evidence on the relative reliability of different water-lifting technologies. This study comparatively evaluated the operational performance of the BluePump against the Afridev, India Mark II and PB Mark II handpumps. The field assessment took place in Turkana County (northern Kenya) and The Gambia, contexts with contrasting environmental, social and institutional characteristics. When controlling for other variables, in both study sites the BluePump had significantly lower odds of a breakdown occurring over a 12-month period compared with other handpumps. The BluePump also had significantly lower odds of a nonfunctional status relative to the Afridev in Turkana, though no significant effect on functionality was observed relative to the India Mark II in either study site or the PB Mark II in The Gambia. In Turkana, the impact of fewer breakdowns on operational uptime and point-in-time functionality may have been moderated by a subsidised maintenance service for which communities pay a fixed annual fee irrespective of handpump type and breakdown frequency. In The Gambia, the BluePump had significantly longer breakdowns than Mark II handpumps because of a problematic maintenance model. The results indicate that technological innovations such as the BluePump can lead to operational improvements, but technology alone is no panacea and the long-term sustainability of water supplies ultimately depends upon the effectiveness of maintenance services.

Groundwater is now a major source of agricultural water supply in many parts of the world. The value of groundwater as a new source of supply is well known. However, its additional buffering or stabilization value is less appreciated and even less analysed. Knowledge on groundwater’s stabilization value is advanced by developing and estimating an empirical model using the case of tank irrigation systems in Tamil Nadu, India. Unlike previous work, the model uses cross-sectional rather than time-series data. The results show that for the case-study region, the stabilization function added approximately 15% to supply value. Scenarios with surface water and electricity price were incorporated in the model. Increased surface-water supply and electricity price caused reduction in groundwater use but the percent of stabilization value of groundwater increased. The findings are used both to suggest improvements in tank irrigation systems and to further contextualize knowledge of groundwater’s stabilization value.

Worldwide, coastal aquifers are threatened by seawater intrusion. The threat is greatest when aquifers are overexploited or when recharge is low due to a semi-arid or arid climate. The Kaluvelli-Pondicherry sedimentary basin in Tamil Nadu (India) presents both these characteristics. Groundwater levels in the Vanur aquifer can reach 50 m below sea level at less than 20 km inland. This groundwater depletion is due to an exponential increase in extraction for irrigation over 35 years. No seawater intrusion has yet been detected, but a sulphate-rich mineralization is observed, the result of upward vertical leakage from the underlying Ramanathapuram aquifer. To characterize the mechanisms involved, and to facilitate effective water management, hydrogeological numerical modelling of this multi-layered system has been conducted. Existing and acquired geological and hydrodynamic data have been applied to a quasi-3D hydrogeological model, NEWSAM. Recharge had been previously quantified through the inter-comparison of hydrological models, based on climatological and surface-flow field measurements. Sensitivity tests on parameters and boundary conditions associated with the sea were performed. The resulting water balances for each aquifer led to hypotheses of (1) an offshore fresh groundwater stock, and (2) a reversal and increase of the upward leakage from the Ramanathapuram aquifer, thus corroborating the hypothesis proposed to explain geochemical results of the previous study, and denying a seawater intrusion. Palaeo-climate review supports the existence of favourable hydro-climatological conditions to replenish an offshore groundwater stock of the Vanur aquifer in the past. The extent of this fresh groundwater stock was calculated using the Kooi and Groen method.

A hydrological study of four streambed recharge structures, locally called check dams, in a monsoonal area of hard-rock terrain in Rajasthan, India, was conducted over 3 years to evaluate their contribution to agricultural production. Their catchment area totalled 3,003 ha, and mean annual recharge from the 4 impoundments was 779,000 m³ or 26 mm. The calculated components of the annual water balance of these check dams are presented, together with a sensitivity analysis on unmeasured parameters and documentation of capital and maintenance costs of check dams. The maximum recharge was found to occur in the wettest year for the two structures on first-order streams; however, for the two structures on second-order streams, the maximum recharge occurred in the average rainfall year because, at these sites, groundwater levels rose so that the stream became hydraulically connected to the aquifer for a period in the wettest year causing mean dry weather infiltration rates to diminish. The study also evaluated the effect of manual desilting and mechanical desilting on mean dry-weather-infiltration rate. For the check dam that was manually desilted, the recharge increased by 84% over that of the preceding year, whereas for the mechanically desilted check dam it reduced by 18%, and the two control check dams increased by 13%. A present value analysis for net benefits of additional crop production attributable to recharge from check dams indicated that, after accounting for average annual maintenance costs 2.9% of capital costs, the benefit:cost ratio of the four check dams averaged 4.1. Hence this study shows that these check dams are economically attractive at the local level for securing irrigation water supplies.

The groundwater abstracted at a well field near the Yamuna River in Central Delhi, India, has elevated ammonium (NH₄ ⁺) concentrations up to 35 mg/L and arsenic (As) concentrations up to 0.146 mg/L, constituting a problem with the provision of safe drinking and irrigation water. Infiltrating sewage-contaminated river water is the primary source of the NH₄ ⁺ contamination in the aquifer, leading to reducing conditions which probably trigger the release of geogenic As. These conclusions are based on the evaluation of six 8–27-m deep drillings, and 13 surface-water and 69 groundwater samples collected during seven field campaigns (2012–2013). Results indicate that losing stream conditions prevail and the river water infiltrates into the shallow floodplain aquifer (up to 16 m thickness), which consists of a 1–2-m thick layer of calcareous nodules (locally known as kankar) overlain by medium sand. Because of its higher hydraulic conductivity (3.7 × 10⁻³ m/s, as opposed to 3.5 × 10⁻⁴ m/s in the sand), the kankar layer serves as the main pathway for the infiltrating water. However, the NH₄ ⁺ plume front advances more rapidly in the sand layer because of its significantly lower cation exchange capacity. Elevated As concentrations were only observed within the NH₄ ⁺ plume indicating a causal connection with the infiltrating reducing river water.