INTRODUCTION TO WATER QUALITY SURVEILLANCE.
RATIONALE: The World Health Organisation (WHO) estimates that about 94% of diarrhoeal cases are preventable through modifications to the environment, including interventions to increase the availability of clean water, and to improve sanitation and hygiene. In addition, a 2005 systematic review concluded that diarrhoeal episodes are reduced by 25% through improving water supply, 32% by improving sanitation, and 45% through improved personal hygiene.
In Zambia, the problem of contaminated drinking water in rural and peri-urban areas is exacerbated by unplanned settlements, insufficient number of improved water sources, overcrowding, poor sanitation and indiscriminate dumping of solid waste. This justifies the carrying out of on-site water monitoring.
Water is essential for life, health and human dignity. In extreme situations, there may not be sufficient water available to meet basic needs, and in these cases supplying a survival level of safe drinking water is of critical importance. In most cases, the main health problems are caused by poor hygiene due to insufficient water and by consumption of contaminated water. Diseases related to inadequate water, sanitation and hygiene are a huge burden in developing countries. It is estimated 88% of diarrhoeal diseases is caused by unsafe water supply, inadequate sanitation and hygiene (WHO, 2004C).
Benefits from Improved Water Availability:
There are a number of potential benefits to improved access to water supply, in addition to the reduction of disease. The reason that many communities give for placing a high priority on improved water supply usually relate to benefits other than health. These benefits are of particular importance to women. A closer, clearer source of water can produce immediate and far-reaching improvements on women’s lives.
Convenience:
Most people, when identifying improved access to water as a priority, are thinking of convenience. Everybody wants water as close as possible to their homes simply because it is convenient. As such convenience is also related to the security of women. Water closer to home can minimize the chances of abduction or assault.
Time Saved:
Energy Saved:
Studies have shown that women walk long distances to collect water can burn as much as 600 calories or more per day, which may be one of their nutritional in-take. Closer sources of water can thus improve the nutritional status of women and children (and hence health and wellbeing).
Money Saved:
In many communities, especially in poor urban areas, households continue to have to buy water from vendors, often at exorbitant rates. Such different financial costs can absorb up to 30% of total household cash income. Measures that improve the availability of water to reduce its cost and are therefore of direct benefit to families and particularly to women, who are often responsible for finding the funds to pay for water.
Prevention of injury:
When girls are forced to carry heavy loads of water over longer distances, there is a danger of lasting spinal column and pelvis injury and deformation. Closer water sources minimize this.
Adequacy of Supply:
As the drinking water supply surveillance agency has an interest in the health of the population at large, its interest extends beyond water quality to include all aspects of the adequacy of drinking-water supply for the supply for the protection of public health.
If the performance of a community water-supply system is to be properly evaluated, a number of factors must be considered. Some countries that have developed national strategies for the surveillance and quality control of water supply systems have adopted qualitative service indicators for application at community, regional and national levels.
In undertaking an assessment of the adequacy of the drinking-water supply, the following basic service parameters of a drinking-water supply should normally be taken into consideration.
These usually include:
Quality: the proportion of the population using water from different levels of drinking-water supply (e.g. no access, basic access, intermediate access and optional access)
Coverage: (accessibility}: the percentage of the population that has a recognizable (usually public) water supply system.
Quantity: the average volume of water used by consumers for domestic purposes (expressed as litres per capita per day).
Continuity: the percentage of the time during which water is available (daily, weekly or seasonally).
Cost: the tariff paid by domestic consumers
Accessibility:
From the public health standpoint, the proportion of the population with reliable access to safe drinking-water is the most important single indicator of the overall success of a drinking-water supply programme. There are a number of definitions of access (or coverage), many with qualifications regarding safety or adequacy. The preferred definition is that used by WHO and UNICEF in their Joint Monitoring Programme, which defines reasonable access to improved sources as being availability of at least 20 litres per person per day within one kilometer of the users dwelling. Improved and unimproved water supply technologies in the WHO/UNICEF Joint Monitoring Programme have been defined in terms of providing reasonable access, as summarized below:
Improved water technologies:
Household connections
Public stand pipe
Borehole
Protected dug well
Protected spring
Rain water collection (but not from the first rains)
Unimproved water technologies:
Unprotected well
Unprotected spring
Vendor provided water
Bottled water
Tanker truck provided water
Key Indicators of Water Quality and Accessibility include:
Average water for drinking, cooking and personal hygiene in any household is at least 15 litres per person per day
The maximum distance from any household to the nearest water point is 500 meters
Queuing time at a water source is not more than 15 minutes
It takes not more than 3 minutes to fill a 20 litre container
Water sources and systems are maintained such that appropriate quantities of water are available consistently or on a regular basis
Queuing Time: Excessive queuing times are indicators of insufficient water availability (either due to an inadequate number of water points or inadequate yields of water points. The potential results of excessive queuing times are:
Reduced per capita water consumption
Increased consumption from unprotected surface sources and
Reduced time for water collectors to tend to essential survival task
Affordability:
The affordability of water has a significant influence on the use of water and selection of water sources. Households with the lowest levels of access to safe water supply frequently pay more for their water than do households connected to a piped water system. The high cost of water may force households to use alternative sources of water of poorer quality that represent a greater risk to health. Furthermore, high costs of water may reduce the volumes of water used by households, which in turn may influence hygiene practices and increase risks of disease transmission. When assessing affordability, it is important to collect data on the price at the point of purchase. Where households are connected to the drinking-water supplier, this will be the tariff applied. Where water households are connected to the drinking-water supplier, this will be the tariff applied. Where water is purchased from public standpipes or from neighbours, the price at the point of purchase may be very different from the drinking-water supplier tariff. Many alternative water sources (notably vendors) also involve costs, and these costs should be included in evaluations of affordability. In addition to recurrent costs, the costs for initial acquisition should also be considered when evaluating affordability
Continuity:
Interruptions to drinking-water supply either through intermittent sources or resulting from engineering inefficiencies are a major determinant of the access to and quality of drinking-water. Analysis of data on continuity of supply requires the consideration of several components. Continuity can be classified as follows:
Year-round service from a reliable source with no interruption of flow at the tap or source
Year-round service with frequent (daily or weekly) interruptions, of which the most common causes are:
Restricted pumping regimes in pumped systems, whether planned or due to power failure or sporadic failure
Peak demand exceeding the flow capacity of the transmission mains or the capacity of the reservoir
Excessive leakage with the distribution system
Excessive demands on community-managed point sources
Seasonal service variation resulting from source fluctuation, which typically has three causes:
Natural variation in source volume during the year
Volume limitation because of competition with other uses such as irrigation
Periods of high turbidity when the source water may be untreatable; and
Compounded frequent and seasonal discontinuity
This classification reflects broad categories of continuity, which are likely to affect hygiene in different ways. Daily or weekly discontinuity results in low supply pressure and a consequent risk of in-pipe recontamination. Other consequences include reduced availability and lower volume use, which adversely affect hygiene. Household water storage may be necessary, and this may lead to an increase in the risk of contamination during such storage and associated handling. Seasonal discontinuity often forces users to obtain water from inferior and distant sources. As a consequence, in addition to the obvious reduction in quality and quantity, time is lost in water collection.
Objectives Of Water Supply Quality Control:
Human Health:
Much of the ill-health which affects humanity, especially in the developing countries can be traced to lack of safe water and wholesome water supply generally good and adequate sanitation. There can be no state of position health and wellbeing without safe water. Water is a universal requirement for organic life is essential for survival. People require water on a daily basis and can survive extended starvation but not sustained lack of water.
Water has been a prominent source of human infectious diseases throughout history, causing large outbreaks of diarrhoeal diseases and death as will be seen at a later stage in the case of a recent cholera outbreak in Zambia. The infection can impair both physical and mental development as well as reduce the ability to work in adults. It is estimated that worldwide disease burden from water, sanitation and hygiene to be 4% of the total disease burden worldwide. Diarrhoeal infections are now much less common in developed countries because of:
Improved drinking water treatment
Sewerage disposal systems
Public Health infrastructure
However in developing countries, still cause significant morbidity and mortality due to lack of adequate drinking water and poor sanitation
Physiological and Hygiene Needs:
The basic physiological requirements for drinking water have been estimated at about 2 litres per capita per day. This is just an estimate for survival. But from the standpoint of Public health and improvement of quality of life, water should be provided in adequate volume. It will help to reduce the incidence of many water related diseases among people most at risk.
The consumption of water, however, depends on climate conditions, standards of living and habits of people. A daily supply of 150-200 litres per capita is considered as an adequate supply to meet the needs for urban domestic purposes. Besides drinking, water is used for cleaning, preparing food, bathing, washing clothes and equipment, flushing waste, irrigation, crops, extinguishing fires, swimming, transporting goods and people.
Water Quality/Quantity:
Absolutely pure water is never found in nature. Absolutely pure water is that which contains only two parts of Hydrogen and one part of Oxygen by volume and nothing else. But the water found in nature contains a number of impurities in varying amounts. The rain water which is originally pure. also absorbs various gases and other impurities while falling. We remove impurities only into certain extent so that it may not be harmful to the public health. The water treated in this way is called WHOLESOME water. In other ways wholesome water is that water which is not CHEMICALLY PURE, but does not contain anything harmful to human health. The following are the requirements of wholesome water:
It should be free from bacteria which may cause disease
It should be colourless and sparkling which may be accepted by the public
It should be tasteless, and odour-free
It should not corrode pipes
It should be free from all objectionable matter e.g. foreign matter of the kind such as sewage etc
It should have dissolved oxygen and free carbonic acid so that it may remain fresh
Water Quality
Drinking water, or potable water, is defined as having acceptable quality in terms of its physical, chemical, bacteriological and acceptability parameters so that it can be safely used for drinking and cooking (WHO, 2004). WHO defines drinking water to be safe as long as it does not cause any significant health risks over a long time of consumption, and an effort should be made to maintain drinking-water quality at the highest level possible.
WHO and the Zambia Bureau of Standards (ZABS) consider the basic quality requirements of drinking water as outlined below. These requirements cover the basic hazards of contaminated water to human health and the distribution infrastructure:
It should be acceptable to the consumer. Bad taste or colour, staining, or unpleasant odour can cause a user to choose an alternative source
It should be free from disease-causing organisms
It should be free from toxic chemicals
Quantity (service level)
The quantity of water collected and used by households has an important influence on health. There is a basic human physiological requirement for water to maintain adequate hydration and an additional requirement for food preparation.
There is further requirement for water to support hygiene, which is necessary for health. Estimates of the volume of water needed for health purposes vary widely. In deriving WHO guideline values, it is assumed that the daily per capita consumption of drinking-water is approximately 2 litres for adults, although actual consumption varies according to climate, activity level and diet. Based on currently available data, a minimum volume of 7.5 litres per capita per day will provide sufficient water for hydration and incorporation into food for most people under most conditions. In addition, adequate domestic water is needed for food preparation, laundry and personal and domestic hygiene, which are important for health. Water may also be important in income generation and amenity uses. The quantities of water collected and used by households are primarily a function of the distance to the water supply of total collection time required. This broadly equates to the level of service. Four levels of service can be defined, as shown in service level is useful and easily measured indicator that provides a valid surrogate for the quantity of collected by households and is the preferred indicator for surveillance. Available evidence indicates that health gains accrue from improving service level in two key stages: the delivery of water 1 km or 30 minutes total collection time; and when supplied to a yard level of service. Further, health gains are likely to occur once water is supplied through multiple taps, as this will increase water availability for diverge hygienic practices. The volume of water collected may also depend on the reliability and cost of water. Therefore, collection of data on these indicators is important.
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