40% of this amount is supposed to be used for operating costs at the village level and 60% is paid into funds for maintenance, renewal and new investments as well as for a support unit at the regional level. the water tariff for rural areas in this part of the country thus is higher than the national urban water tariff for residential users charged by onea. affordability. according to a water tariff study by icen and sogreah carried out in 2007 the average onea residential water bill was 4,400 cfaf (us$8.80) per month for a household connection using 45 liter per capita and day, corresponding to about 4% of household income. it was estimated that households that fetched water from standpipes paid 2,600 cfaf (us$5.20) or 3% of their income to receive 28 liter per capita and day. external cooperation a joint aid strategy for burkina faso is expected in 2009 following in the footsteps of a "plan d'action national de l'efficacité de l'aide" (panea). among the main external partners in the water and sanitation sector in burkina faso are the african development bank, the arab bank for economic development in africa, denmark, the kuwait fund for arab and economic development, the european investment bank, the european union, france, germany, the islamic development bank, the opec fund for international development, the west african development bank and the world bank. the donors increasingly finance projects together in the spirit of the paris declaration on aid effectiveness, thus reducing the fragmentation of external cooperation. in addition to public donor agencies, many ngos are active in water and sanitation in burkina faso. public partners projects jointly funded by multiple donors. the us$270m ouagadougou water supply project (2001–2007), which secured the water supply of the capital through the ziga dam and associated infrastructure, was supported by 11 donors convened by the world bank. germany. german development cooperation supports water and sanitation projects and programs implemented by onea as well as the decentralized directorates of the ministries and regional authorities. it supported the improvement and expansion of the water supply of bobo-dioulasso as well as the collection and treatment of industrial and household sewage in the same city. together with 13 other donors, germany was also involved in the construction of the ziga dam which ensures a continuous water supply for the population of ouagadougou and the population living around the reservoir. another german project promotes water supply in fada n’gourma. german cooperation also supports the construction and rehabilitation of tube wells in rural areas in the boucle du mouhoun province and in five provinces of the eastern region. germany also supports the provision of water supply and sanitation for households, schools and hospitals in small and medium towns in the country's southwest. unicef. unicef is particularly active in school water supply and sanitation, as well as in hygiene education through schools. it has helped to provide schools with 170 wells and rehabilitate 50 water pumps. this has contributed to reducing the prevalence of guinea worm infection from 1,956 cases in 2000 to 30 cases in 2005 and also to increasing water access in schools from 39% to 82% over the same period. sanitation and hygiene education was intensified, using primary schools as an entry point: 139 schools were equipped with special latrines, teacher and students were trained in hygiene education, and children participated in activities targeting behavior change in families. non-governmental organizations wateraid. following a pilot project that began in 2001, wateraid began developing partnerships and programmes in the rural garango, ramongo and bokin districts. in 2003 work extended to include bogodogo and sigh-noghin districts in ouagadougou. wateraid now works with seven partner organisations. according to its website, it helped over 32,000 people gain access to clean water and started a credit scheme for sanitation and soap-making enterprises with women. initiative: eau. initiative: eau is an american nonprofit, non-governmental organization dedicated to increasing the safety and quality of drinking water services in developing areas and crisis zones. the organization has its west africa regional office in fada n'gourma and currently operates in the east, center east, and sahel regions of burkina, engaging in water infrastructure and quality surveillance. through its research initiatives, it has monitored water quality for over 15 000 individuals and works strategically with the government and public water utility to inform decision-making.