在全球范围内，死亡和患病总人数的7%左右是水污染造成的，每年有300～400万人死于水传播的疾病。亚洲和非洲死亡总人数的8.5%和7.7%是由腹泻引起的。在减少这种死亡人数方面已经取得很大进展，由于饮水、环境卫生、个人卫生和医疗条件的改善，例如采用口服补液疗法，每年死于腹泻疾病的总人数（其中大多数是儿童）从1982年的460万人减少到2002年的180万人，原因是单沿海水域污水污染引起的水传播疾病的社会成本相当于每年损失400万人工年，这意味着每年经济损失达160亿美元。
非洲最近取得的一项成就是通过改善供水和个人卫生，开展宣传运动，改善监测网络，从而在消灭麦地那龙线虫疾病方面取得很大进展。报告的病例从1986年的350万个病例减少到2000年的7.5万个病例，下降幅度为98%。
近年来，在主要河流遭受严重污染之后，经合组织改善了这些河流的水质，目前对市政污水和工业排水采用了先进的废水处理设施，还采用了比较清洁的工业生产工艺，限制使用农业化学品，减少使用低磷酸盐等污染物质，这些措施增加了水中的氧气含量，减少了金属、多氯联苯和其他有毒化学品的含量，增加了鱼的数量和品种。但是，某些有毒化学品依然构成严重的问题。广泛的数据收集系统定期提供关于水质的可靠信息。对于莱茵河和多瑙河等国际河流，现已设立国际河流委员会以确保采取一致行动。
工业化世界为管制废水排量进行大量投资，但是，发展中世界90%的废水依然未经处理而排入当地河流和溪水。现有的废水处理设施通常都不可靠，效率低下。尼泊尔、中亚、中国（黄河）和印度（恒河）的河流污染严重。这些国家以及其他国家已经开始执行控制污染的方案，包括制定立法，提高民众的认识，开展以社区为主的监测以及建立强有力的实施机制。例如，目前圣保罗市正在作出这种努力，通过环境卫生和水处理系统使已经无生物的铁特河重新恢复生机。许多含水层、尤其是发展中国家大城市地下的含水层也受到污染，但是污染程度不明。孟加拉国和印度孟加拉邦存在另一个严重问题，那里大约有3500万人饮用砷污染的天然地下水，面临危险。
在发展中地区的城市边缘区，人们往往用未经处理的市政污水和废水作小型灌溉之用，尤其是用于种植蔬菜，污水因营养丰富而使蔬菜生长茂盛。但是这种做法给人体健康造成严重威胁。在有些国家，特别是缺水的西亚和地中海国家，经过处理的废水被作为一种水源，常被用于灌溉。如果废水处理效果较好，这种用途可能是安全的，虽然人们还存在一些顾虑，如果废水处理不够充分有效和可靠，粮食作物可能受到污染。
在发展中国家的发展方案中，水质管理基本上都没有得到充分重视。由于需要大量资本，现有资金有限，机构能力薄弱，公众认识和需求有限以及消费者付款能力较差等原因，市政废水和工业废水处理进展特别缓慢。政府普遍采用预防原则和污染者付清理费原则，但是，由于缺乏资源和施政不良，实施水质条例和标准依然受到限制。
原文如下：
Water quality and health
Globally, contaminated water is still responsible for approximately 7 per cent of all deaths and diseases, with 3-4 million people dying each year of waterborne diseases. Diarrhoea alone is responsible for 8.5 per cent and 7.7 per cent of all deaths in Asia and Africa, respectively. Considerable progress has been made in reducing that toll, with the total number of people dying each year of diarrhoeal diseases, most of whom are children, declining from 4.6 million in 1982 to 1.8 million in 2002, owing to improvements in drinking water, sanitation, hygiene and medical treatment, such as oral rehydration therapy. The social costs of waterborne diseases caused by sewage pollution of coastal waters alone amounts to 4 million person-years lost per year, representing an economic loss of $16 billion a year.
One recent success in Africa has been major progress in the eradication of guinea worm disease through improved water and hygiene interventions, public awareness campaigns and improved monitoring networks. Reported cases dropped from 3,500,000 in 1986 to 75,000 in 2000, a decline of 98 per cent.
OECD countries have improved the quality of the water in major rivers in recent years after they had become seriously polluted. Advanced wastewatertreatment facilities for both municipal sewage and industrial effluent, cleaner industrial production processes, restrictions on agricultural chemicals, and less polluting materials, such as low-phosphate detergents, have improved the oxygen content of the water, reduced concentrations of metals, PCBs and other toxic chemicals, and increased the numbers and variety of fish. However, some toxic chemicals remain a challenge. Extensive data-collection systems provide regular and reliable information on water quality. On international rivers, such as the Rhine and Danube, international river commissions have been established to ensure concerted action.
While the industrialized world has made huge investments in controlling wastewater discharges, 90 per cent of wastewater in the developing world still goes untreated into local rivers and streams. Where wastewater-treatment facilities exist, they are usually unreliable and inefficient. Rivers of Nepal, Central Asia, China (Yellow River) and India (Ganges) are highly polluted. Those and other countries have started pollution-control programmes, including legislation, public awareness raising, community-based monitoring, and stronger enforcement mechanisms. Such efforts are under way in S?o Paulo, for example, to bring the biologically dead Tiete River back to life through sanitation and water treatmen systems. Many aquifers are also polluted, especially beneath major cities of developing countries, but the degree is unknown. Another serious problem exists in Bangladesh and the State of West Bengal in India, where about 35 million people are at risk from drinking arsenic-contaminated groundwater of natural origin.
In peri-urban areas in developing regions, untreated municipal sewage and wastewater is often used for small-scale irrigation, especially for growing vegetables that thrive on nutrient-rich sewage, but that poses serious threats to human health. In some countries, particularly water-scarce countries of West Asia and the Mediterranean, treated wastewater is used as a source of water, usually for irrigation. Depending on the effectiveness of the treatment, such uses can be safe, although there are concerns that food crops could be contaminated if the treatment is not fully effective and reliable.
By and large, in developing countries, water-quality control has not received adequate attention in development programmes. Progress has been especially slow in the treatment of municipal and industrial wastewater because of its capital intensity, limited availability of financial resources, weak institutional capacities, limited public awareness and demand, and poor payment capacities of consumers.
Both the precautionary and the polluter-pays principles are widely endorsed by Governments, but enforcement of water-quality regulations and standards remains constrained by lack of resources and poor governance.
