A wide range of substances can drastically harm both public health and the environment. Hazardous substances that might be present in drinking water mainly include pathogens (microorganisms) and contaminants (inorganic chemicals, organic chemicals and metals). Contamination of drinking water with pathogens including bacteria, viruses, parasitic protozoa and helminths is the major factor for prevalence of diseases in developing countries. Faeces infiltrating drinking water sources are most often responsible for contamination with pathogens. Likewise, contaminants in drinking water originating from both human activities (anthropogenic) and natural processes (geogenic) incorporate large health risks depending on their concentration.
All waters (i.e. surface water, groundwater/aquifers) can become contaminated from many types of human activities as well as from natural sources. Agricultural, commercial, industrial, and residential development can all contribute to groundwater contamination (WALLIN 1997).
Examples of activities that could negatively affect groundwater if not managed properly include:
Contaminants percolate permeable soil layers together with infiltrating water. Once reaching groundwater level, they spread not only horizontally but usually also vertically throughout the whole groundwater body (WAL 2010).
The concentration of most pathogens (but not necessarily chemicals) decreases gradually with depth as they are decomposed. Hence, in unconfined aquifers or if a confined aquifer is beyond the reach of available drilling technologies, wells should be drilled as deep as possible (WAL 2010). In a confined aquifer, the impermeable layer prevents contaminants from further vertical migration into the underlying aquifer making groundwater below this layer free from surficial contamination. As a consequence, confined aquifers generally are less susceptible to contamination (WAL 2010).
While soluble contaminants (e.g. pathogens, water-soluble contaminants, heavy metals, etc.) mix with groundwater, insoluble contaminants (e.g. oil or many solvents like trichloroethene (TCE)) do not mix with or dissolve as easily. Consequently, they accumulate either on the groundwater level or at the top of an impervious layer depending on their density.
Drinking water contamination result in poor drinking water quality and can cause a loss of a community’s drinking water supply, high restoration costs, high costs for providing alternative drinking water supplies, and a high potential for community health problems. Additionally, contaminants can adversely affect environmental systems and causing the provision of ecosystem functions to fail.
Waterborne or excreta related diseases are still significant causes of mortality and morbidity in many developing countries. The transmission routes of these and the health risk factors involved are important, in order to design and implement or modify excreta use schemes so that the transmission of these diseases are reduced (see also health risk management). The pathogens of concern for environmental transmission through faeces mainly cause gastrointestinal symptoms such as diarrhoea, vomiting and stomach cramps. Several may also cause symptoms involving other organs and severe sequels or be an interrelated factor for malnutrition. Major pathogens may be viruses, bacteria, parasitic protozoa, and helminthes. The table below summarises the most common organisms in each category and the signs and symptoms or disease associated with them:
Campylobacteriosis (diarrhoea, cramping, abdominal pain, fever, nausea; arthritis; Guillain-Barré syndrome)
Escherichia coli (EIEC, EPEC, ETEC, EHEC)
Typhoid/paratyphoid fever (headache, fever, malaise, anorexia, bradycardia, splenomegaly, cough)
Salmonellosis (diarrhoea, fever, abdominal cramps)
Shigellosis (dysentery - bloody diarrhoea, vomiting, cramps, fever; Reiter’s syndrome)
Yersinioses (fever, abdominal pain, diarrhoea, joint pains, rash)
Enteric adenovirus 40 and 41
Calicivirus (incl. Noroviruses)
Various: respiratory illness, enteritis, viral meningitis
Aseptic meningitis, encephalitis (often asymptomatic)
Enterovirus types 68-71
Meningitis, encephalitis, paralysis
Hepatitis (fever, malaise, anorexia, nausea, abdominal discomfort, jaundice)
Poliomyelitis (often asymptomatic, fever, nausea, vomiting, headache, paralysis)
Cryptosporidiosis (watery diarrhoea, abdominal cramps and pain)
(often asymptomatic; diarrhoea; abdominal pain)
Amoebiasis (often asymptomatic, dysentery, abdominal discomfort, fever, chills)
Giardiasis (diarrhoea, abdominal cramps, malaise, weight loss)
Helminthes (parasitic worms)
Ascariasis (generally no or few symptoms; wheezing; coughing; fever; enteritis; pulmonary eosinophilia)
Trichuriasis(unapparent through vague digestive tract distress to emaciation with dry skin and diarrhoea)
(Itch; rash; cough; anaemia; protein deficiency)
All infections related to faeces are likewise representative for anal cleansing and ablution water. Infections related to faeces have traditionally been centred on enteric pathogenic bacteria. In developing countries with insufficiently functioning sanitation systems, outbreaks of cholera, typhoid and shigellosis still are of major concern. Among the bacteria, at least Salmonella, Campylobacter and Enterohaemorrhagic E. coli (EHEC) are of general importance, both in industrialised and developing countries, when microbial risks from various fertiliser products are considered, including faeces, sewage sludge or animal manure.
More than 120 different types of viruses may be excreted in faeces, including members of the enteroviruses, rotavirus, enteric adenoviruses and human caliciviruses (noroviruses) groups. Hepatitis A is also of major concern and the importance of Hepatitis E is emerging, when applying wastes to land and is considered a risk for both water- and food- borne outbreaks, especially when the sanitary standard are low.
The parasitic protozoa, Cryptosporidium and Giardia are occurring with high prevalence as an enteric pathogen. Entamoeba histolytica is also recognised as an infection of concern in developing countries. Others like Cyclospora and Isospora may also be of concern.
In developing countries, geohelminth infections are of major concern. The eggs (ova), of especially Ascaris and Taenia are very persistent in the environment. Hookworm disease is widespread in most tropics and subtropics areas, and affects nearly one billion people worldwide. These infections exaggerate malnutrition. The eggs from Ascaris and hookworms that are excreted in the faeces require a latency period and favourable conditions in soil or deposited faeces to hatch into larvae and become infectious.
Schistosoma haematobium are excreted both in faeces and urine while other types of Schistosoma, e.g. S. japonicum and S. mansoni are just excreted in faeces. More than 200 million people are currently infected with Schistosomiasis. The use of treated excreta should not have an impact but fresh or untreated faecal material, which should not be used, constitute a risk when applied close to fresh water sources where the snail is present.
Environmental transmission of urinary excreted pathogens is of limited concern in temperate climates, but any faecal cross-contamination that may occur by misplacement of faeces in the urine-diverting toilet ends up in the urine fraction and is a determinant of possible health risk. Also in tropical climates, faecal contamination of collected urine may be considered as the greatest risk but some urinary-transmitted pathogens also need to be considered. The pathogens excreted in urine are Leptospira interrogans, Salmonella typhi, Salmonella paratyphi and Schistosoma haematobium. There is a range of other pathogens, including some of the human viruses that have been detected in urine but their presence may normally be considered insignificant for further risk of environmental transmission.
The main hazard of greywater is, as for urine, due to faecal cross-contamination. Faecal contamination is limited in amounts when one is considering the traditional fractions of greywater, like washing faecally contaminated laundry (i.e. diapers), childcare and showering. If anal cleansing is combined in greywater the risk is enhanced. In many situations, other sources of faecal contamination in greywater occurs, but is often forgotten or not considered in a system perspective. In reality, these will be the main drivers for the subsequent microbial health risks.
See also use of urine and faeces in agriculture.
The infectious organisms are released from the bodies of infected persons in their excreta, eventually reaching other people, that may be infected via either the mouth, for example when being in contact with contaminated areas and accidentally transmitting minute quantities to the mouth, when contaminated crops are eaten or when drinking contaminated water) or through contact with the skin (e.g., hookworm and schistosomiasis) or through inhalation of contaminated aerosols or particulate material.
The relative importance of these pathogens in causing illnesses depends in addition on a number of factors including their persistence in the environment, minimum infective dose, ability to induce human immunity, and latency periods (SHUVAL et al. 1986). Thus pathogens with a higher probability of causing infections are those that:
The amount and variability of the pathogens will depend mainly on the infection among the population served and the scale of the sanitation system (see also health risk management). Thus, in low income countries, where there is a high prevalence of excreta related diseases, a greater number of pathogens are more likely to be introduced into a sanitation systems, compared to a developed countries where the prevalence of such diseases is generally low (see also toilet systems).
The incidence rate of a disease is the yearly number of reported cases divided by the total population, often expressed per 100 000 people. The incidence will vary due to the prevailing epidemiological situation within an area. The reported number of cases is often substantially underestimated and pathogens causing less severe symptoms are less likely to be reported. The disease incidence and excretion factors will, in general terms, give their concentration at the time of excretion and the subsequent risks will relate to environmental persistence and die-off, dilution factors, exposure and the dose that humans are exposed to. The later further relate to the efficiency of technical and behavioural barriers within the system context (see also health risk management).
Inorganic chemicals comprise some of the most common and mobile contaminants in groundwater. Such contaminants include nitrate, ammonia, sodium, chloride, fluoride, and arsenic. Nitrate contamination from sewage and agricultural practices occurs over large areas. Salt in groundwater can be the result of the upwelling of highly mineralised geothermal or sea water in coastal areas, and road de-icing. Fluoride and arsenic can occur naturally in areas containing sediments derived from igneous rocks. Nitrate and chloride do not adsorb readily on to soil materials and can be transported great distances.
E.g. nitrate, ammonia, sodium, chloride, fluoride, cyanide, arsenic, etc.
Organic compounds are carbon and hydrogen-based chemicals, some of which occur naturally. However, it is mainly the human-produced chemicals that are of concern. These chemicals include solvents, pesticides, and other industrial chemicals. Organic chemicals are removed from groundwater by chemical reactions and microbial activity. Many organic compounds, however, particularly those containing chlorine, can remain in the subsurface for many years. Many organic chemicals are highly toxic and cause severe health problems such as birth defects and cancer.
E.g. petro-chemicals (oil, diesel), plastic, solvents, pesticides, chlorine, paint, etc.
Metals, including heavy metals, are also of environmental concern. The transport of metals is controlled by their solubility. The solubility of metals is dependent on pH. The pH of water can be affected by acid drainage from mining activities. Dissolved metals can also be adsorbed onto large organic molecules in water and be transported by them.
HESPERIAN FOUNDATION (Editor); UNDP (Editor) (2004): Sanitation and Cleanliness for a Healthy Environment. Berkeley: The Hesperian Foundation. URL [Accessed: 17.04.2012]. PDF
OTTOSSON (2003): Hygiene Aspects of Greywater and Greywater Reuse. Royal Institute of Technology/ Swedish Institute of Infectious Disease Control.
SHUVAL, H.I.; ADIN, A.; FATTAL, B.; RAWITZ, E.; YEKUTIEL, P. (1986): Wastewater Irrigation in Developing Countries. Health Effects and Technical Solutions. Washington, D.C.: The World Bank. URL [Accessed: 27.03.2012].
STENSTROEM, A.; SEIDU, R.; EKANE, M.; ZURBRUEGG, C. (2011): Microbial Exposure and Health Assessments in Sanitation Technologies and Systems. Stockholm: Stockholm Environment Institute (SEI). URL [Accessed: 28.11.2011]. PDF
WAL, A. van der (2010): Understanding Groundwater & Wells in Manual Drilling. Instruction Handbook for Manual Drilling Teams on Hydro-geology for Well Drilling, Well Installation and Well Development. Papendrecht: Practica Foundation. URL [Accessed: 21.03.2012].
WALLIN, R. (1997): Wellhead Protection: A Guide for Arizona Communities. TUCSON: Arizona Department of Environmental Quality, Water Quality Division. URL [Accessed: 17.04.2012]. PDF
BARRETT, M. (2002): Groundwater and Sanitation; Nutrient Recycling and Waterborne Disease Cycles. Stockholm: EcoSanRes, Stockholm Environmental Institute. URL [Accessed: 11.10.2010]. PDF
A short summary about the waterborne disease cycle. Groundwater is often contaminated with pathogens which originate from human excreta. Therefore, the aim should be to break the waterborne disease cycle. At the same time, it should be possible to use excreta as nutrients without contaminating groundwater. The author proposes some methods how this can be reached.
CONFALONIERI, U.; MENNE, B.; AKHTAR, R.; EBI, K.L.; HAUENGUE, M.; KOVATS, R.S.; REVICH, B.; WOODWARD, A.; Parry, M.L. (Editor); Canziani, O.F. (Editor); Palutikof, J.P. (Editor); Linden, P.J. van der (Editor); Hanson, C.E. (Editor) (2007): Human Health. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press. PDF
A chapter about the impacts of climate change on human health. There is evidence that the climate change altered the distribution of some infectious disease vectors. The burden of diarrhoeal diseases will increase as well as the number of people which suffer from dengue as just to cite some effects of the ongoing climate change.
COTRUVO, J.A.; DUFOUR, A.; REES, G.; BATRAM, J.; CARR, J.; CLIVER, D.O.; CRAUN, G.F.; FAYER, R.; GANNON, V.P.J. (2004): Waterborne Zoonoses: Identification, Causes, and Control. Geneva: World Health Organisation (WHO). URL [Accessed: 11.10.2010]. PDF
An encyclopaedia which contains everything about waterborne diseases. It handles also the prevention, the controls and risk of these diseases as well as the description of them. Furthermore, the document contains an outlook for the future.
HAVELAAR, A. H.; MELSE, J. M. (2003): Quantifying Public Health Risk in the WHO Guidelines for Drinking Water Quality. Geneva: World Health Organisation (WHO). URL [Accessed: 11.10.2010]. PDF
This edition of WHO Guidelines contains a preventive management framework for safe drinking water. The framework provides the methodology of DALY (Disability Adjusted Life Years), which allows an exact classification of diseases. This can help to evaluate health priorities.
A comprehensive book on recycling human excrement without chemicals, high technology or pollution. Well written, practical, and thoroughly researched, this self-published book is built on nearly twenty years of experience by the author, who tells us about every aspect of dealing with excrement on the home-scale level. Only available for free as web book.
JIMENEZ, B.; NAVARRO, I.; MAYA, C. (Editor) (n.y.): Pathogens in Dry Sanitations Systems and Risk of Using Sludge Produced in Agriculture. Mexico: University of Coyocan. URL [Accessed: 06.10.2010]. PDF
A paper about the most common pathogens which exist in faecal sludge and how to control these.
This is a comprehensive report on why toilets matter. The report is rich in infographics, provides overview of the sanitation crisis and the related burden of disease in developing countries.
WHO (Editor) (2007): Chemical Safety of Drinking Water Assessing Priorities for Risk Management. Geneva: World Health Organization (WHO). URL [Accessed: 12.10.2011]. PDF
Identifying and prioritizing chemical risks presents a challenge, especially in developing countries, because information on the presence of chemicals in water supplies is often lacking. This document provides guidance to help readers to meet that challenge. It shows how information on aspects such as geology and industrial and agricultural development, which is often readily available, can be used to identify potential chemical contaminants (and potential sources of chemicals), from catchment to consumer, and thus prioritize risks. This is a supporting document to the Guidelines for Drinking-water Quality (WHO 2008 and WHO 2011), and it is aimed at policy-makers, regulators, managers and public health practitioners at national and local level.
WHO (Editor) (2007): Combating Waterborne Diseases at the Household Level. The International Network to Promote Household Water Treatment and Safe Storage. Geneva: World Health Organisation (WHO). URL [Accessed: 11.10.2010]. PDF
This document is divided into three main parts. The first part contains an introduction to the topic and depicts some possible, simple techniques for treating water at the household level. The second part describes the possibility of collaborating to fight against waterborne diseases and the last part presents again some low-cost solutions.
UNEP (2013): Costs of Inaction on the Sound Management of Chemicals. UNEP. URL [Accessed: 28.03.2013]. PDF
This document provides a practical assessment of the current state of knowledge of the economic costs of inaction on the sound management of chemicals. It aims to raise political awareness of the benefits stated in economic terms of providing resources to sound management of chemicals and to strengthen the rationale for inclusion of sound chemicals management priorities into national development policies and plans. It also aspires to build capacity for ongoing assessment at international, national, and local levels through demonstration and practical application of proven techniques. The report includes an extensive literary review in order to identify economic information on the health, environmental, and development planning effects of harmful chemicals. Chemicals reviewed within the scope of study include industrial, minerals and metals, agricultural, household chemicals and pharmaceuticals among others.
Graham, J.; Polizotto, M.L. (2013): Pit Latrines and Their Impacts on Groundwater Quality: a systematic Review. Advance Publication. In: Environmental Health Perspectives. URL [Accessed: 09.04.2013]. PDF
This study reviews empirical studies on the impact of pit latrines on groundwater quality and identifies knowledge gaps regarding the potential and consequences of groundwater contamination by latrines.
This toolkit, intended for practitioners interested in behavior change, is organized into four modules: Behaviour Change, Sustainability, Integration and Results. Each has reports and presentations about the lessons learned from previous projects, as well as mass media, direct consumer contact, and interpersonal communication tools used throughout previous projects.
RHEINGANS, R. (Editor); CUMMING, O. (Editor); ANDERSON, J. (Editor); SHOWALTER, J. (Editor) (2012): Estimating Inequities in Sanitation-related Disease Burden and Estimating the Potential Impacts of Propoor Targeting. London: London School of Hygiene and Tropical Medicine. URL [Accessed: 16.03.2012]. PDF
The objectives of this study are to model for 10 low-income countries in sub-Saharan Africa and South Asia: 1) The distribution of sanitation-related health burden by wealth quintile; 2) The distribution of health benefits for targeting different wealth quintile groups; 3) The spatial distribution of sanitation-related health burden and benefits
CONTZEN, N.; MOSLER, H.J. (2012): Factors Determining the Effectiveness of Oxfam’s Public Health Promotion Approach in Haiti. Duebendorf: Swiss Federal Institute of Aquatic Science and Technology (EAWAG). URL [Accessed: 24.04.2012]. PDF
In response to the devastating Earthquake of January 12th 2010 and the cholera outbreak of October of that same year Oxfam Great Britain, Oxfam Quebec and Intermón Oxfam conducted public health promotion and cholera response in Haiti. Different promotion activities were applied which aimed at changing hygiene behavior by changing perceptions and beliefs about healthy behaviors amongst people affected by crisis. In February 2011 four Oxfam affiliates in Haiti in partnership with a team of behavior change researchers from Eawag launched the present research project to do an in-depth evaluation of the promotional activities that had been conducted with the goal of further improving the WASH situation for people in Haiti and worldwide by understanding how to make hygiene promotion more effective. The main focus of the research project was around the question which specific promotion activities were strongly associated with perceptions and beliefs about handwashing with soap and were thus capable of changing handwashing behavior at key times.
OXFAM (Editor) (2012): Hygiene Promotion: Determining what Works. Cholera Response in Haiti. Boston: Oxfam International. URL [Accessed: 24.04.2012]. PDF
When a massive earthquake struck Haiti in January 2010, followed by a cholera epidemic that broke out in October of that year, Oxfam rushed assistance—clean water, sanitation, and hygiene materials and information—to hard-hit areas to protect public health.
GEORGE, R. (2012): Dirty Little Secret: The Loo that Saves Lives in Liberia. London: The Guardian. URL [Accessed: 13.02.2012]. PDF
Diarrhoea kills more children than HIV/Aids, tuberculosis and malaria combined – and its main cause is food and water contaminated with human waste. Liberia's president is trying to change all that.
The Broad Street cholera outbreak was a severe outbreak of cholera that occurred near Broad Street in Soho district of London, England in 1854. This outbreak is best known for the discovery that cholera is spread by contaminated water. This discovery came to influence public health and the construction of improved sanitation facilities beginning in the 19th century.
WSP (Editor) (2012): Behavioral Determinants of Handwashing with Soap Among Mothers and Caretakers: Emergent Learning from Senegal and Peru. Washington, D.C: Water and Sanitation Program (WSP). URL [Accessed: 27.02.2012]. PDF
A new Water and Sanitation Program (WSP) Learning Note found that beliefs and ease of access to soap and water were correlated with handwashing with soap behaviors for given proxy measures among mothers and caretakers in Peru and Senegal.
Thematic factsheet. Every day, 2 million tons of human wastes are disposed of in watercourses, and in developing countries 70 % of industrial wastes are dumped untreated into waters where they pollute the usable water supply. But not only industry contaminates our water resources, so do also agriculture. The contribution of the food sector to the production of organic water pollutants, are in high-income countries 40 % and in low-income countries 54 %.
EAWAG (Editor); SANDEC (Editor) (2008): Environmental Health. Lecture notes. Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 23.05.2012]. PDF
This book contains information on environmental health aspects of water and sanitation. It contains a definition of environmental health, describes various water-related diseases and also hygiene approaches. There is also a related PowerPoint to this document.
EAWAG (Editor); SANDEC (Editor) (2008): Environmental Health. Presentation. Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 23.05.2012]. PDF
This PowerPoint presentation contains information on environmental health aspects of water and sanitation. It contains a definition of environmental health, describes various water-related diseases and also hygiene approaches. There is also a related lecture to this document.
http://www.who.int/water_sanitation_health/en/ [Accessed: 01.06.2010]
This website is a description of the WHO’s work on water, sanitation and hygiene as well as an interesting collection of documents on the issues.
http://www.cdc.gov/ [Accessed: 07.10.2010]
This homepage by the Centres for Disease Control and Prevention provides an overview about global water, sanitation and hygiene topics.
http://water.epa.gov [Accessed: 19.12.2011]
National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. Visit the list of regulated contaminants with links for more details.