of the households should be able to pay the full-cost tariff of $1 per m3 efficiency the number of employees per 1000 connections is an indicator of the technical efficiency of utilities. in sub-saharan africa, the average is 6. the highest efficiency is observed in south africa, where the four utilities need 2.1–4.0 employees per 1000 connections. rwanda peaks with 38.6 employees per 1000 connections. another indicator is the share of non-revenue water (water that is lost or not metered). in an efficiently managed system, this amount is below 25%. in 2005 it was estimated to be 20% in senegal, 18% in burkina faso, 16% for the water utility corporation in botswana, 14% in windhoek in namibia and 12% in drakenstein, south africa. these utilities have achieved levels of non-revenue water similar to levels in oecd countries. however, in other african countries the level of non-revenue water is extremely high: for example, it exceeds 45% in zambia, is more than 60% in maputo (water supply and sanitation in mozambique|mozambique), 75% in lindi (water supply and sanitation in tanzania|tanzania) and 80% in kaduna (nigeria). few data are available for efficiency in the rural space. expenditures in sub-saharan africa, current spending on water supply and sanitation (investments, operation and maintenance) totals to $7.6 billion per year, or 1.19% of the regional gdp. this includes $4.7 billion per year for investments (2001-2005 average). according to the world bank, total expenditures are less than half of what would be required to achieve the millennium development goals in sub-saharan africa; that would need more than $16.5 billion per year or 2.6% of the regional gdp. the african development bank estimates that $12 billion is required annually to cover africa's needs in improved water supply and sanitation. expenditures are often not well targeted. according to a world bank study, there is a large gap in expenditures between rural and urban areas, in particular capital cities. public expenditures go to where they are most easily spent rather than where they are most urgently needed. sanitation receives only a small part of public expenditures: low household demand for sanitation results in politicians not seeing sanitation as a vote winner, and therefore allocating scarce resources to sectors with higher perceived political rewards. financing out of the $4.7 billion of investments in water supply and sanitation in sub-saharan africa, 70% is financed internally and only 30% is financed externally (2001-2005 average). most of the internal financing is household self-finance ($2.1bn), which is primarily for on-site sanitation such as pit latrines. public sector financing ($1.2bn) is almost as high as external financing (us$1.4bn). the contribution of private commercial financing has been negligible at $10 million only. the share of external financing varies greatly. in the 2001-2005 period official development assistance financed 71% of investments in benin, 68% in tanzania, 63% in kenya, 43% in the dr of congo, 34% in south africa, 13% in nigeria and less than 1% in côte d'ivoire or botswana. according to another world bank study of 5 countries, in the 2002-2008 period official development assistance financed on average 62% of public expenditures on water and sanitation. the share varied from 83% in sierra leone to 23% in the republic of congo. external cooperation in 2008, $1.6 billion of foreign aid flowed into the water supply and sanitation sector in sub-saharan africa, which is 4% of all development aid disbursed to sub-saharan africa. this foreign aid covered 21% of all expenditures in water supply and sanitation in sub-saharan africa, and was principally directed to investments in infrastructure. operation and maintenance is financed by the national governments and consumer revenues. the largest donors to water supply and sanitation in sub-saharan africa are the world bank, the eu institutions, the african development fund, and bilateral assistance from germany and the netherlands. the united states, although they are the largest donor in sub-saharan africa in absolute numbers, play a marginal role in the water supply and sanitation sector. total aid to ssa, in m$ and % of total aid to ssa in wss, in m$ and % of total world bank (ida) 4 856 (12.3%) 378 (24.1%) eu institutions 5 056 (12.8%) 266 (16.6%) african development fund 1 780 (4.5%) 193 (12.0%) germany 2 906 (7.4%) 171 (10.7%) the netherlands 1 446 (3.7%) 137 (8.5%) united states 6 875 (17.4%) 13 (0.8%) total received by ssa 39 451 (100%) 1 603 (100%) especially in the poorer countries the presence of many different donors and western ngos puts a strain on the coherence of national strategies, such as in burkina faso and ethiopia. foreign aid comes in at all levels: the central government, the national social funds, the utilities, the local authorities, local ngos,... although most foreign actors try to inscribe their aid in the existing national structures, their implementation approaches and technical solutions often differ. strategies for improvement the final report on africa's infrastructure, has the following recommendations for the water supply and sanitation sector: continue the institutional reforms: more efficient internal processes, increased autonomy of the utilities, better performance monitoring improve the efficacy of governmental expenditure experiment with different models to connect the unconnected, since investments in piped networks cannot keep pace with urban growth devise socially fair tariffs that nonetheless cover the real cost of water supply and sanitation improve the understanding of groundwater extraction in urban areas, since this is the fastest growing source of improved water supply.