By this stage in your study of the Module you should have a good understanding of the reasons why safe water is important, and of the main components of a water supply system. You have also learned about some of the ways in which the safety of a water supply can be compromised. Water safety is the focus of this study session.
The World Health Organization (WHO) promotes the use of Water Safety Plans as a method by which the risks in supplying safe water are assessed and controlled. In this study session you will learn about Water Safety Plans and the steps involved in drawing up such a plan for an urban water supply system. The study session concludes with details of a Water Safety Plan formulated in Ethiopia.
When you have studied this session, you should be able to:
8.1 Define and use correctly all of the key words printed in bold. (SAQ 8.1)
8.2 Explain why a Water Safety Plan is necessary. (SAQ 8.2)
8.3 Describe the different steps in a Water Safety Plan and understand how they are applied. (SAQ 8.3)
8.4 Give an example of the successful use of a Water Safety Plan in Ethiopia. (SAQ 8.4)
A Water Safety Plan is a plan to ensure the safety of drinking water through a risk assessment and management process that considers all the points in water supply from the catchment to the consumer. It is a means of preventing and managing threats to a drinking water supply system, before anything goes wrong, taking into account all the stages of the supply process from the water catchment to the consumer.
What is a water catchment?
From Study Session 4 you know that the catchment is the area of land surrounding and sloping towards a river.
If the water quality assessed at the tap where people collect it or use it is found to be poor, it has the disadvantage that unsafe water may already have been consumed by the people served by the distribution system. The WHO has published recommended steps for drawing up a Water Safety Plan (Bartram et al., 2009) on which the following description is based. By using Water Safety Plans, the quality of the water is proactively managed so that poor-quality water does not reach consumers. Water Safety Plans also help to eliminate the causes of incidents that might disrupt the delivery of safe water to consumers. Incidents, in the context of water supply, means emergencies such as a burst pipe.
A Water Safety Plan considers all the stages in the supply of water, and therefore it involves:
Water Safety Plans put the emphasis on controlling risks where they are likely to arise, rather than having a treatment plant deal with cases of contamination after they have occurred. Preventing a problem from occurring is much better than having it occur and then trying to minimise its impact.
While the primary focus in a Water Safety Plan is on the direct dangers facing safe water quality (such as the possibility of chemical or microbial contamination), the Plan has to be more wide-reaching, considering aspects such as potential for flood damage; the sufficiency of the source water and alternative supplies; availability and reliability of power supplies; the quality of treatment chemicals; the availability of trained staff; security; and the reliability of communication systems.
Water Safety Plans can vary in complexity depending on the scale and type of water supply system being considered. In general, there are ten components in a Water Safety Plan (Figure 8.1).
Although the stages depicted in Figure 8.1 are sequential (i.e. you do them one after another in a sequence), they can be undertaken by teams of people working in parallel, looking at different aspects of water supply. For instance, there could be teams looking separately at the catchment, treatment plant and distribution system. We will now look at each of the steps in turn.
In order to draw up a Water Safety Plan, full information about the water supply system, from the catchment to the taps of consumers, is required. This will include details of the catchment (such as possible sources of contamination), the abstraction point, the pipes (sizes, construction materials, etc.), the units at the treatment plant, the distribution system (piping material, possible weak spots, etc.). To compile this information, a team of experts is required.
The expert team (Figure 8.2) should include not just technical experts but local people because they will be most knowledgeable about what is actually on the ground. Local people may include farmers and forestry workers, landowners, and representatives from industry, other utilities and local government, and consumers. Collectively the team should have the skills required to identify hazards and determine how the associated risks can be controlled. The definitions of hazards and risks are given in Box 8.1, where the difference between them is explained.
The support of senior management is crucial for the formulation and implementation of a Water Safety Plan, because changes in working practices may be needed, as well as new systems (costing money) for the control of risks. The finance and time requirements for preparing the Water Safety Plan will need to be approved by senior management who are the supervisors and decision makers responsible for implementing any actions that may be required. Depending on the context, senior management could be the Town Water Board or the Woreda WASH Team, for example.
Identifying hazards and assessing risks are important aspects of preparing a Water Safety Plan. A hazard is something that is known to cause harm. Bartram et al. (2009) define a hazard as ‘a physical, biological, chemical or radiological agent that can cause harm to public health’. Risk is the likelihood or probability of the hazard occurring and the magnitude of the resulting effects.
Here is a simple example. If you climb a ladder, you know there is a chance you could fall off and be injured, although it is unlikely. The ladder is the hazard and the likelihood of your falling off and hurting yourself is the risk. Risk assessment is about evaluating a situation to determine how likely it is that the potential harm from the hazard will happen.
The water supply system (Figure 8.3(a)) has to be fully described. This will allow hazards to be identified, and risks to be assessed and managed. In many cases, this information will be available and will only need reviewing to ensure that it is up to date, and checked for accuracy through site visits. A flow diagram that shows all the major elements of the water supply system (Figure 8.3(b)) should be drawn.
In the case of springs and wells, it is important to know where the rainfall is percolating into the ground to replenish the groundwater. This will highlight the area where protective measures (such as restrictions on, say, fertiliser or pesticide use) are needed so that contaminants are not carried by the rainwater into the groundwater.
It is important to identify the potential hazards at each stage of the water supply process (see Box 8.1). Hazardous events in this context are defined as events that can introduce hazards into the water supply. A hazardous event can also be considered a source of a hazard. Table 8.1 gives examples of hazardous events and hazards that can affect different parts of a water supply system.
|Hazardous event (source of hazard)||Associated hazard||Component of water supply system affected|
|Agriculture||Microbial contamination from animal excreta, pesticides, nitrates from fertiliser use||Catchment|
|Interruption of power supply||Interruption of treatment||Treatment|
|Disruption of disinfection due to lack of disinfectant supply||Unsafe water goes to consumers||Treatment|
|Mains burst||Contaminants getting into pipeline||Distribution network|
|Illegal connections||Contamination of water supply by back-siphonage||Distribution network|
Site visits are an effective way of ensuring all possibilities are covered (Figure 8.4). It is important to speak to the people who work at the locations concerned as they will have local knowledge that may not necessarily be in the paperwork related to the facility.
Risk is the likelihood of a hazard affecting the water supply system. A risk assessment can be carried out if the risk and the severity of the associated hazard are known. A method of undertaking a risk assessment quantitatively is to use a risk matrix as shown in Figure 8.5 (Bartram et al, 2009). The severity of the impact of a hazard and its likelihood can be multiplied together to arrive at a figure that indicates its risk score. The risk rating will be determined by this risk score, as shown at the bottom of Figure 8.5.
To illustrate this application of a risk matrix, suppose you wanted to carry out a risk assessment for the case where a treatment plant runs out of chlorine disinfectant (Figure 8.6). In a properly managed plant, with a system of stock control in place, such an occurrence may be rare (with a rating of 1). The public health impact of it, however, will be catastrophic (with a rating of 5). Using the matrix in Figure 8.5, you can calculate a risk score, which will be the product of 1 and 5. This risk score of 5 can then be given a risk rating. From the scale in Figure 8.5, this would be ‘low’ (being less than 6).
By repeating the exercise for other hazards and risks and comparing the risk scores, a prioritised list can be drawn up that ranks the risks in order of importance. Unfortunately, budgets are often limited and because of this many of the smaller risks are disregarded.
This means identifying the precautions (control measures) that need to be in place to eliminate or minimise the risks to the water supply system. So, in the example above, you would need to have a system of stock control that tells you when chlorine stocks are running low. Stock control may use some form of manual record keeping in a book or an electronic system (Figure 8.7). These have to be checked for effectiveness, as part of the Plan, and improved if necessary.
A system of regular monitoring has to be established to check that the control measures are working. Again, using the example above, someone will have to check that the records of chlorine availability in the store match what is actually present.
A set of clear instructions to enable the whole water supply system to be operated as desired has to be in place. If there is an incident that disrupts the normal operation of the system – for instance, if a control measure fails – then a number of actions need to be followed. These should be documented in the management procedures so that they are easy to refer to and apply. The relevant management procedure will detail the remedial measure, what communications to undertake and the steps to follow in an investigation of the failure.
Do you remember the usual name for the routine instructions for operating a water treatment plant?
They are often referred to as standard operating procedures or SOPs.
Following through the example of chlorine stock, if the supply were to run out, the management procedure might suggest contacting nearby water utilities (using names and telephone numbers of contact persons who had previously been consulted) for a loan of an amount of chlorine. An alternative might be to contact supply companies that could rapidly acquire and supply the chemical (but this is likely to be at a high cost!). The population affected by the break in supply would have to be informed of the crisis, possibly by messages on local radio and television programmes. Lastly, an investigation needs to be undertaken as to how the crisis came about, and how it can be prevented from recurring.
The verification programme is to check that all the components of the water supply system are working properly, and that water of a suitable quality and quantity is being supplied to the population, and therefore that the Water Safety Plan is working. There are three activities that together provide evidence that a Water Safety Plan is working effectively:
In compliance monitoring, sampling and analysis of the water is undertaken to verify that the water quality standards are being met (complied with). For microbial verification, indicator organisms such as E. coli or faecal coliforms are looked for at representative points in the water supply system. In appropriate cases (say in areas with a Cryptosporidium problem), measurement of the organisms may be necessary. For chemical parameters, direct measurement is carried out, rather than the use of an indicator.
In internal and external auditing, scrutiny of the operational practice is undertaken by an auditor in person to verify that good practice is in place. As the names suggest, internal audits are undertaken by someone from within an organisation and external audits by an independent, objective auditor from outside an organisation. Auditors will, for instance, identify areas where procedures are not being followed, resources are inadequate or training is required for staff.
Assessment of customer satisfaction is the third aspect of verification and this is undertaken by personally meeting with representative consumers to obtain their feedback on the quality of the water delivered to them.
Supporting programmes are activities that support the development of people’s skills and knowledge in relation to delivering safe water. These mainly involve training, and research and development. To ensure that the Water Safety Plan is current, staff need to be updated on changes in the water supply system, and the revised actions they need to take in times of emergency. In the case of the chlorine supply running out, an investigation of the crisis will reveal whether staff retraining has to be conducted, or if the system for monitoring chlorine stocks needs to be modified, or indeed if both need to be done. The Water Safety Plan will have to be reviewed as a consequence.
Supplementary programmes include sessions to educate members of the public on how they can ensure that the water supply is kept safe (for example, by giving them information on how back-siphonage can contaminate the water distribution system).
All the sections detailed above have to be documented so that there is an audit trail, in case any step has to be reviewed. (An audit trail is a chronological record that provides documentary evidence of the sequence of activities that led to a given decision.) Keeping clear and complete documentation enables the Plan to be reviewed periodically. This is important because changes can happen anywhere along the water supply process. New risks might arise, or more efficient and economical methods might become available to control the different risks.
In addition to regular review and updating, it is important that the Plan is reviewed and possibly modified following an incident or crisis. A post-incident review, where the incident is discussed in detail, is likely to identify areas for improvement in the operating procedures, training or communications, and these should be incorporated in a revised Water Safety Plan.
In Hentalo Wejerat woreda, in Tigray Region, Water Safety Plans were used to improve water supplies in small communities and ensure access to safe and clean water (Drop of Water, 2014).
Twelve individuals were trained as Trainers in Water Safety Planning by specialists from the World Health Organization. The training covered the principles of water safety planning, risk management for the supply of drinking water, guidance on developing Water Safety Plans, surveillance and control of small community water supplies, and safe practices in household water use. Three Water Safety Planning Teams were then established.
The three Water Safety Planning Teams were given training that focused on the impact of unsafe water, assessing environmental contaminants, operating a hygienic water point and the physical treatment of water at household level. They then applied Water Safety Plans to three water points at Lemlem Queiha, May Weyni and May Yordanos.
At Lemlem Queiha, although there was a fence at the water point, there was no gate. The area around the water point was unclean, and the water point was vulnerable to flooding. Not all the houses in the vicinity had latrines, which meant open defecation was taking place. The community had a poor awareness of good hygiene and sanitation. Jerrycans used for collecting water were unclean.
At May Weyni, the fence at the water point had been damaged by flood and had not been repaired, and there was no gate. Nearly all the residents had latrines at their homes.
At May Yordanos, the water point was found to be clean and well fenced. Water handling was hygienic both at the water point and in the residents’ homes. The houses had latrines, which meant that open defecation was eliminated. The community had a good awareness of hygiene and sanitation.
Over the one-year period of the project, with the aid of the Water Safety Planning Teams most of the residents installed latrines, and gained a good knowledge of hygiene and sanitation. The water points were kept clean, and good water-handling practice was adopted at water points and in homes. Open defecation was almost totally eliminated. Gates were installed at the water points at Lemlem Queiha and May Weyni, and the broken fence at May Weyni was repaired, to prevent contamination by animals.
In what ways does Case Study 8.1 correspond to the ten steps of Water Safety Plans described in this study session?
The actions taken in the case study correspond to the first few steps in a Water Safely Plan:
Less well-fulfilled steps were:
The above was an example of the application of a Water Safety Plan but in a rural context. Hence not all the ten steps necessary in an urban situation were applicable to achieve the positive outcome.
In Study Session 8 you have learned that:
Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering the following questions.
Match the following words to their correct definitions.
Using the following two lists, match each numbered item with the correct letter.
Water Safety Plan
a.the chance of a hazard occurring
b.anything that can cause harm
d.analysis of water to check that it is within standards
e.training programmes that contribute to the delivery of safe water
f.the process by which the likelihood of harm from a potential hazard is assessed
g.documentation of the sequence of activities that led to a given decision
h.a plan that proactively seeks to identify and control risks to safe and continuous water supply
i.an event that can introduce a hazard to a water supply
Explain briefly why a Water Safety Plan is necessary.
A Water Safety Plan is necessary to ensure that the water that is produced and delivered to consumers is safe. It also ensures that the chance of an incident disrupting the continuous supply of water is minimised.
Arrange the steps of the Water Safety Plan shown below in the right order:
The correct order is:
Look at Figure 8.8, which shows a well that is the sole water source for a village. Based on what you can see in the photograph, undertake the following:
Your answers should be along the following lines:
Hazard assessment: The well is open and presents several hazards. There is no wall around it, so people or animals can contaminate the water easily, either by entering the water, or by people using contaminated utensils or containers when collecting water. There is a possibility of surface water running into it, and also wind-blown debris entering the water.
Risk assessment: The risk of contamination is high, especially since it is the sole source of water for the village, so the risk assessment score will also be high.
Identification of control measures needed for each risk: A metre-high concrete wall around the well will be an effective means of preventing direct contact with the water. A rope-and-pulley system should be set up with a bucket so that water can be drawn from the well. This water can then be put into containers brought by the people. A wall will also keep out surface run-off and wind-blown debris.
Definition of the monitoring system for each control measure: Regular inspection (say, monthly) of the wall must be undertaken to ensure that it is not cracked. The pulley-and-bucket system should also be checked (say, weekly) to ensure that it is working properly and is kept clean. The bucket should be checked for cracks.
In the Water Safety Plan implemented in Hentalo Wejerat woreda, what were the changes made that improved the safety of the water supply?
The following measures improved the safety of the water supply: