Water Sanitation Health

Questions and answers: South Asia earthquake and tsunami

The information below gives responses to questions that are likely to be frequently asked during an emergency. They are divided into four categories as shown in the Table of Contents—Health risks linked to drinking-water and sanitation; health risks due to stagnant water; immediate actions that should be taken in respect of water, hygiene, and sanitation; and the nature of WHO's response to the emergency.

Health risks: Drinking-water and sanitation

What actions are most urgent in relation to water, sanitation and health?

The three top priorities are the provision of sufficient quantities of safe water, basic sanitation arrangements and promotion of good hygiene behaviours.

The first priority is to provide an adequate quantity of water, even if its safety cannot be guaranteed, and to protect water sources from contamination. A minimum of 15 litres per person per day should be provided as soon as possible, though in the immediate post-impact period, it may be necessary to limit treated water to a minimum of 7.5 litres per day per person. During emergencies, people may use an untreated water source for laundry, bathing, etc. Water-quality improvements can be made over succeeding days or weeks.

Major health risks due to inadequate excreta disposal arise after disasters. Where normal sanitation structures have been damaged or destroyed it is essential to provide toilet facilities immediately. Emergency facilities are usually provisional and need to be progressively improved or replaced as the situation develops.

Following damage to existing systems, or when parts of a city receive large numbers of displaced or homeless people, so putting increased pressure on facilities that may already be under strain, a rapid assessment of damage and needs is required to decide what emergency actions to take.

Designated defecation fields or areas can be used where enough space is available. These work best in hot, dry climates and should be clearly marked, fenced (if possible), and protected against flooding. They should be located downwind and away from living areas, avoid water courses, and at a reasonable distance (minimum 50m) from water points. Shovels should be provided to families so that they can dig small holes to defecate into and cover their faeces with soil. Collective trench latrines may also be an option. In longer term situations or after the initial emergency period has subsided, it may be more practical to build simple pit latrines, ventilated improved pit (VIP) latrines, or poor-flush latrines. In situations where the soil is rocky or the ground water is very close to the surface, elevated platforms may be constructed. Latrines of all types need to be properly cleaned and maintained. Responsibilities for cleaning and maintaining latrines should be clearly spelled out. For collective latrines it may be necessary to hire someone to take care of them.

The immediate response may also include establishing or reinforcing sewage evacuation services, to bypass blocked sewers or to carry out intensive septic tank or latrine emptying in periurban areas. Every effort should be made to allow people to use their existing toilets, through temporary repairs to broken sewers and sewage treatment works.

In all cases, good hygiene practices are very important for preventing disease transmission. Water should be provided in sufficient quantities to enable proper hygiene. Hands should be washed immediately after defecation, after handling babies' faeces, before preparing food and before eating.

Other environmental health interventions might be crucial as indicated in the subsequent questions and answers.

What water, sanitation and hygiene behaviours are most important for protecting health during an emergency?
  • Make every effort to drink water which has been disinfected (preferably filtered and disinfected) or boiled. Protect water sources from contamination.
  • Dispose of faeces safely (especially the faeces of babies and people with diarrhoea) in latrines or special areas that will not lead to exposure of community members or contamination of water sources (surface or ground water).
  • Wash hands thoroughly with soap, after defecation, after handling babies' faeces, and before preparing or eating food.
What are the greatest drinking-water and sanitation dangers to human health, and who are the most vulnerable groups?

Infectious disease transmission is the greatest risk after an emergency. The diseases and conditions of ill-health directly associated with water, sanitation and hygiene include infectious diarrhoea (which, in turn, includes cholera, salmonellosis, shigellosis, amoebiasis and a number of other protozoal and viral infections), typhoid and paratyphoid fevers, acute hepatitis A, acute hepatitis E and F, schistosomiasis, trachoma, intestinal helminth infections (including ascariasis, trichuriasis and hookworm infection), dracunculiasis, scabies, dengue, leptopirosis, the filariases (including lymphatic filariasis and onchocerciasis), malaria, Japanese encephalitis, West Nile virus infection, yellow fever and impetigo. Not all these diseases are relevant to all the affected countries. The spread of most of these diseases is of special concern where sanitation systems are disrupted and where excreta has been distributed widely by flooding. The most vulnerable groups are children under five and the elderly. About 90 per cent of the deaths due to diarrhoea occur in children under 5.

Although infectious diseases will pose the greatest health risks, in some cases toxic chemicals may enter water supplies, especially when there has been massive flooding.

Drinking water sources away from sources of chemical or microbial contamination should be used as supplies. If this is not possible, alternative supplies of water may be required (e.g., bottled water or supplies through tanker trucks).

Are there any risks which may become increasingly acute as the time since a disaster evolves?

The length of time that people spend in temporary settlements is an important determinant of the risk of disease transmission which might lead to major epidemics. The prolonged mass settlement of in temporary shelters with only minimal provision for essential personal hygiene is typical of a situation that may cause epidemic outbreaks of infectious diseases.

The main risks of epidemics come from unsanitary conditions and can include, for example, typhoid, dysentery, cholera, and diarrohea. Leptospirosis may also be transmitted through contaminated water or food stuffs that have been contaminated by the urine of infected rats or other animals. Diseases related to overcrowded conditions such as respiratory infections, typhus, and infestations from scabies and lice are also of concern. Diseases spread through mosquito vectors such as malaria, dengue, and Japanese encephalitis may also arise when disease vectors are allowed to breed in stagnant water or even standing water in old tires, cans, etc. Communities may be especially vulnerable to vector-borne diseases when they are living without shelter or access to bed nets.

What is the minimum quantity of water needed?

Based on estimates of requirements of lactating women who engage in moderate physical activity in above-average temperatures, a minimum of 7.5 litres per capita per day will meet the requirements of most people under most conditions. This water needs to be of a quality that represents a tolerable level of risk. However, in an emergency situation, a minimum of 15 litres is required. A higher quantity of about 20 litres per capita per day should be assured to take care of basic hygiene needs and basic food hygiene. Laundry/bathing might require higher amounts unless carried out at source.

What are good indications that water is safe?

In an emergency it should be assumed that all water is at risk of contamination and this includes piped supplies. Thus until told by authorities or having inspected and tested the water it should ideally be treated.

The quality of urban drinking-water supplies is particularly at risk following structurally damaging disasters. Water treatment works may be damaged, causing untreated or partially treated water to be distributed, and sewers and water transmission pipes may be broken, causing contamination of drinking-water in the distribution system.

Floods may contaminate wells, boreholes and surface water sources with faecal matter washed from the ground surface or from overflowing latrines and sewers.

Where there is evidence of faecal contamination of the drinking-water supply, it may be necessary either to modify the treatment of existing sources or to temporarily use alternative sources of drinking-water. It may be necessary to increase disinfection at source or to rechlorinate during distribution. In emergencies, such as during outbreaks of potentially waterborne disease or when faecal contamination of a drinking-water supply is detected, the concentration of free chlorine should be increased to greater than 0.5 mg/litre throughout the system as a minimum immediate response.

Should all water used for domestic purposes be treated?

Not necessarily. However, if you do no have the assurance from the local health agencies or the water utilities that the water is safe then you should disinfect it using one of the different home water treatment methods available.

Are there disease risks from dead bodies and what should be done for safe disposal?

The widespread belief that corpses pose a major health risk is inaccurate. Especially if death resulted from trauma, bodies are very unlikely to cause outbreaks of diseases such as typhoid fever, cholera or plague though they may transmit gastroenteritis or food poisoning syndrome for survivors if they contaminate streams, wells or other water sources.

What are the health risks related to overcrowding?

For communities, inadequate shelter and overcrowding are major factors in the transmission of diseases with epidemic potential such as acute respiratory infections, meningitis, typhus, cholera, scabies, etc. Outbreaks of disease are more frequent and more severe when the population density is high.

Other public structures such as health facilities not only represent a concentrated area of patients but also a concentrated area of germs. In an emergency, the number of hospital-associated infections will typically rise. Decreasing overcrowding by providing extra facilities and a proper organization of the sites or services in health-care facilities is a priority.