Waterborne diseases are diseases transmitted through drinking water contaminated with pathogenic microorganisms such as protozoa, viruses, bacteria, and intestinal parasites. Most waterborne diseases are characterised by diarrhoea and can result in dehydration and even death in very serious cases.
Poor personal hygiene practices like preparing, eating or handling food and water without washing hands well after defecation can lead to contamination due to faecal matter that contains disease-causing microorganisms. Contamination can also occur at the source or while transmitting water through pipes that are located close to sewage lines. This can lead to the mixing of sewage with drinking water, contaminating it with disease-causing microorganisms. Other factors such as inadequate water supply, poor sanitary conditions, uncovered sources of drinking water, defecation in the open near sources of drinking water, poor systems for human waste disposal and a lack of awareness among populations can increase chances of contamination. Natural disasters such as floods can also trigger epidemics of water borne diseases due to mixing of sewage with drinking water sources, drinking of contaminated water due to destruction of safe sources of drinking water.
Waterborne diseases are a serious problem from the public health point of view as they can spread rapidly affecting large sections of the population, lead to a very high disease burden and have a major impact on the economy in countries such as India where water pollution and open defecation, coupled with poor sanitation and hygiene practices lead to high incidence of waterborne diseases.
Waterborne diseases can be classified based on the causative agent and the modes of transmission.
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Some of the common diarrhoeal diseases in India include:
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Other infections include:
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Read more about Hepatitis A here
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Four percent of global deaths and 5.7 percent of the global disease burden is caused by infectious diseases related to water, sanitation, and hygiene (WASH). Only 19 percent of the world population washes hands with soap and water after contact with excreta, 26 percent people drink water that is occasionally contaminated with faecal bacteria.
As high as 1.9 billion people worldwide use either an unimproved source or an improved source of water that is faecally contaminated, mostly groundwater and rural piped supplies. Microbial contamination of water is widespread in lower- and middle-income countries with faecal contamination being the most prevalent in Africa and Southeast Asia.
Uttar Pradesh has recorded the highest deaths due to diarrhoea followed by West Bengal, Assam, Odisha and Madhya Pradesh.
A large proportion of people do not have access to water within the house, increasing the chances of infections. Surface water sources are highly contaminated in India. Poor sewage disposal mechanisms lead to most of the sewage being drained into rivers and lakes that serve as reservoirs of microbial contamination.
Open defecation is common and the untreated sewage and effluents that are released into the water and soil are laden with various disease-producing bacteria. Poor access to safe water sources and toilets and poor WASH practices lead to high instances of waterborne diseases in the country.
Climate change is predicted to increase the severity of weather-related events such as floods and droughts. India too will be greatly affected by these changes. For example, heavy rains and resultant floods can create conducive environments for numerous waterborne diseases such as diarrhoea, cholera, dysentery, typhoid and other bacterial and viral diseases. Evidence shows that rising temperatures and warmer climates can trigger an increased frequency of waterborne diseases such as cholera, giardiasis, salmonellosis, and cryptosporidiosis. Droughts can also trigger waterborne diseases due to increasing water shortages compromising sanitation and hygiene.
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Water is considered ‘safe’ when it is free from pathogenic agents and harmful chemicals, is pleasant to taste and usable for domestic purposes. Good quality water is that which can be safely used for various purposes such as household use, drinking, irrigation, industry, bathing etc.
The World Health Organisation (WHO) has developed international norms on water quality that are used for regulation and to set standards in developing and developed countries. These can be accessed here.
For India, these standards are set by the Bureau of Indian Standards (BIS) and the Indian Standards Institute (ISI). The Indian Standard DRINKING WATER–SPECIFICATION (Second Revision) can be accessed here
While the role of government in improving access to safe water and sanitation is extremely important, a number of steps undertaken at the individual level can also go a long way in preventing diseases through increasing awareness and encouraging hygienic behaviours.
A number of waterborne diseases can be prevented by:
The National Health Policy 2017 reaffirms the government’s commitment to reforming the health sector and achieving universal health coverage. It focuses on disease elimination, reduction in mortality and improvement of health services.
The main strategy to control diseases caused by drinking of contaminated water is providing of safe drinking water. The Government of India supplements the efforts of the states by providing technical and financial assistance under the centrally-sponsored National Rural Drinking Water Programme (NRDWP) for providing safe and adequate drinking water supply facilities in rural areas of the country.
The National Centre for Disease Control (NCDC) provides assistance to state and Union Territory governments to prevent and control waterborne diseases and in investigating outbreaks of such diseases under the Integrated Disease Surveillance Programme (IDSP).
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While waterborne diseases continue to dominate the scene, the condition could worsen with climate change. Adequate preparedness both at the policy level and among citizens is the need of the hour.