hygiene accounts for 4 percent of worldwide deaths and 5.7 percent of worldwide disability-adjusted life years (DALYs) per year (Prüss et al., 2002). Rather than expensive technological solutions designed without local input, there is a need for low-tech, community-based interventions; these interventions have achieved excellent results in health and hygiene, as well as a potential for economic and social benefits.
Water-borne diseases are caused by ingestion of water contaminated with human or animal feces and urine containing pathogens, including cholera, typhoid, amoebic dysentery, campylobacter, salmonella, cryptosporidium, among others. The transmission of these diseases is almost exclusively through diarrhea. Although in healthy, adult patients of more developed countries, it is generally of limited severity and short duration; in vulnerable patients of developing nations, it can be devastating. Worldwide, 1.8 million people die annually from diarrheal disease, 90 percent of whom are children. A WHO analysis looked at relative risks of disease given six different water and sanitation paradigms, from the ideal situation to one without access to clean water or improved sanitation. WHO found that risk increased as fewer had access to services, without piped water, without sanitation services, and little management of the water supply. In the worst-case scenario, the relative risk was 11-fold for diarrheal disease, yet the highly penetrant, water-based systems of developed nations still carried a relative risk of 2.5 from the ideal scenario (Table 7-1).
In developed nations, problems with water distribution systems are significant sources of disease. One-third of outbreaks of gastrointestinal illness in Europe are related to problems with the distribution system (Risebro et al., 2007). Cryptosporidium was associated with many outbreaks because of the inadequate removal during water treatment. As a result, most systems have been improved or removed from service. Major problems in distribution leading to outbreaks include construction or repair complications, low pressure, and damaged or outdated water mains. In the United Kingdom, low water pressure was found to be the strongest association with self-reported diarrheal disease, which could represent 10–15 percent of cases (Hunter et al., 2005).
In developing countries, the problem of distribution is more complex and severe, with many large outbreaks occurring as a result of distribution problems. The risks depend on the system. In the Sudan, for example, some communities use large community water pots into which individuals dip their hands, leading to very high fecal contamination. In Vietnam, some households are able to capture rainwater through roof guttering but many poorer households have roofs made