Water supply and sanitation services in developing countries face a number of challenges which make it difficult for them to meet the Millennium Development Goals. The world population has increased by an average annual rate of 1.3 % since 1990 and currently stands at about 7 billion. Urbanisation around the world has increased from 43 % in 1990 to 51 % in 2010 and the rising trend is expected to continue. This urbanisation, which is highest in developing countries, has led to the mushrooming of informal settlements where water supply and sanitation services are virtually non-existent and waterborne diseases are prevalent. This chapter looks at the challenges for water supply and sanitation in developing countries and uses case studies and examples from Zimbabwe to illustrate typical problems. The problems include lack of investment in the water and sanitation sector, inappropriate technologies, ill-defined institutional frameworks, capacity limitations, and neglect of rural areas. Poor water supply and sanitation in Zimbabwe is typified by the cholera outbreak of 2008/09 which killed nearly 4,300 out of the 99,000 that were affected. The general conclusion of this chapter is that the problem of water supply and sanitation in developing countries requires innovative thinking as it impacts on other areas such as the food and energy sectors. The emphasis should be on appropriate technologies, particularly waterless toilets and natural sewage treatment systems. For water supply, focus should be on demand management and reduction of unaccounted-for water and innovative methods of enhancing revenue collection.