Affiliations: [a] Department of Civil Engineering, University of Nigeria, Nsukka | [b] Center for Environmental Management and Control, University of Nigeria, Enugu Campus
Abstract: Twenty five countries, evenly distributed across the continents were used for this study. The water quality standards of these countries were used to assess water quality data from a water monitoring exercise, based on the CCME water quality index. The ratings obtained were used as a measure of the liberality or strictness of water quality standards of these countries. Afterwards, water quality indices were computed for each of acceptability, health and toxicity. The CCME was then modified to reflect the varying importance of different parameters. The modified water quality index is called the importance averaged water quality index (IAWQI). Going by the overall water quality indices, Australia, UAE, India and Japan seem to have the most stringent drinking water standards; while Jamaica, Peru, Mexico and UAE seem to possess the most liberal drinking water quality standards. England, Italy, Nigeria and Spain have very little or no deviations from WHO guidelines for overall water quality index. Countries such as Jamaica, Peru, USA, Mexico, Ecuador, Rwanda and Ghana have the most negative deviations from the WHO guidelines. In IAWQI, acceptability has a weight of 1.00, health has a value of 11.08 and toxicity has a value of 2.74. A comparison of the CCME WQI and the IAWQI shows that the CCME WQI generally overestimates the quality of water. The IAWQI values of countries such as Sudan, Ghana and Rwanda are much higher than their corresponding WQI values. These three countries located in Africa are among countries with the lowest water poverty indices (WPI).
Keywords: Water quality index, water quality standard, water, water stress
