Geographic Information Systems (GIS) have provided effective and useful methods that are widely used to measure spatial access to services and to inform the planning of public facilities and infrastructures. The development of innovative GIS tools has informed approaches for researching demographic and socioeconomic problems. Nevertheless, GIS methods have not yet been developed for construction of water indices that can provide measures of household accessibility to safe drinking water at the finest spatial scales such as district and sub-district. There has, to date, not been any integrated measurement of access to safe drinking water that can be used as a practical tool to quantitatively identify small areas suffering from poor water supplies or households who use unimproved water sources. A comprehensive and structured review of the literature indicates that although there is international emphasis on drinking water problems in developing countries, there is a wide gap in relation to the current international measurements and programmes set up to measure and monitor access to safe drinking water. This includes efforts made by the United Nations (UN) and the Millennium Development Goals (MDGs) to measure and monitor access to safe water. These measurements are not only limited in terms of the socioeconomic factors impacting safe water access but also have not addressed measurement at the sub-national resolution level of residential communities and spatial variation within individual countries. Therefore, the available measurements neither provide a convincing picture of water accessibility nor a spatially detailed measurement. To bridge this gap, this study introduces new GIS analysis techniques for the measurement of access to safe drinking water as a global problem in the developing world. The main objective is to develop a multivariate index which measures current access to safe drinking water using datasets commonly available in lower and lower middle income countries. It draws on a wider range of data than current United Nations monitoring efforts. GPS coordinates are increasingly collected as a part of household surveys, particularly in the developing world. This offers great opportunities to enhance national census data about drinking water by spatial linkage with other survey sources. Egypt was chosen as a case study and spatial linkage was undertaken between the 2005 Egyptian Demographic and Health Survey (DHS) and the 2006 Egyptian population census in order to develop indicators that reflect household access to safe drinking water. Understanding the spatial uncertainty associated with linking points (DHS GPS clusters) to polygons (sub-governorate census districts) was essential. Consequently, positional error relevant to DHS GPS clusters was detected, validated, measured and modelled. Selection criteria were developed for choosing the index components and a method for scoring these components was implemented. This was followed by standardisation and weighting of the components before combining them all into a single index. A map demonstrating index values for all Egyptian districts has been created. The index was evaluated against health factors to examine the influences of water accessibility on public health. The same types of datasets (DHS and local census) about another country (Jordan) were explored to examine potential index transferability. This was based on assessing the positional accuracy of the GPS clusters of the Jordanian DHS and evaluating the index construction. Potential limitations of this measurement were discussed and recommendations for further research suggested. Future policies options with a wider incorporation and implementation of GIS and spatial analysis methods were also considered