3 Elementary Fluid Dynamics—The Bernoulli Equation

Introduction The provision of water was one of the eight components of primary health care identified by the World Health Assembly in Alma Ata in 1978. The Alma Ata Declaration on Primary Health Care expanded the concept of health care to include broader concepts of affordability, accessibility, self-reliance, inter-sectoral collaboration, community participation, sustainability and social justice. The importance of water supply continues to be emphasised as critical to reducing poverty and improving the health and well-being of the World's children and adults. The global community has committed itself to halving the proportion of the world's population who are unable to reach or to afford safe drinking water by 2015. Although great strides have been made in meeting this challenge in terms of provision of services, the safety of many water supplies remains unknown and uncertain. The recent Global Water Supply and Sanitation Assessment 2000 Report provided statistics regarding access to technologies that were either 'improved' or 'unimproved'. This was done on the assumption that some technologies were likely to be better for health, although it was recognised that would not always be the case. However, there was no information provided on water quality within the assessment. The inclusion of information regarding water quality in future assessments of the degree of access to water supplies is desirable. This handbook is designed to help in the implementation of rapid assessments of water quality to improve the knowledge and understanding of the level of safety of water supplies. There is significant value in reporting of independently verifiable water quality data to support national Governments and the international community in measuring progress in achieving the international development targets. Such data provides useful information regarding current conditions, deriving the likely public health burden relate to inadequate water supply and to gain an understanding of the extent of major water quality problems in developing countries. These data would, therefore, provide an indication of future investment priorities and needs on a country, regional and global basis.