A liquid consumption survey of individuals in greater Cape Town

Master Thesis


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University of Cape Town

There is no published data for the per capita consumption of water of individuals in South Africa. A daily rounded volume of 2 litres per person is usually taken as a working estimate from world wide data. As part of ongoing epidemiological studies into potential health effects of changes in the water supply to greater Town, water consumption patterns were ascertained. As health effects are often spatially ascribed to the place of residence of a person, it was necessary to ascertain how much water was drunk at home as well as away from home. Water consumed was divided into three classes: (i) water consumed from the tap, (ii) commercial beverages and (iii) water bound in food. A review of methods of conducting dietary surveys indicated that a 24-hour recall would be the most appropriate method. Two surveys on total dietary intake utilizing a 24-hour recall were carried out (n = 2 000 persons for each survey), one in winter and the ether in summer. The design of the survey involved a cluster sample of households that were representative of the socio-economic and demographic structure of greater Cape Town. Three pretested types questionnaires were administered by trained interviewers: (i) a placement questionnaire to describe the household composition, (ii) a recall questionnaire for individual adults and children and (iii) a recall questionnaire for babies. Particular attention was paid to the accurate ascertainment of the volumes of food and drink consumed as well as their preparation to facilitate accurate analysis. The water content of each food item was calculated by a computer program that utilized computerized food composition tables. The water consumption data was analyzed by sex, age, population group, income and the season of the year. Detailed graphs and tables are provided. Results were also standardized to the population of greater Cape Town. It was found that the difference in consumption between the White and "Coloured" population groups was greater than the difference between those people of high and low-income groups. The mean total water intake for Whites was 2.19 litres per day, while for "Coloureds" it was 1.26 litres per day. There is no obvious bias to account for this difference. The figures for protein consumed by the two groups, which was used as a control, are consistent with values reported in the literature. Summer consumption was higher than that during winter. The ratio of tap water consumed at home to total liquid consumed was approximately 0.5.