Self-Assessment Questions (SAQs) for Study Session 16
Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering the following questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.
SAQ 16.1 (tests Learning Outcome 16.1)
Which of the following statements is false? In each case explain why it is false.
A E.coli is a type of virus found in faeces.
B Faecal coliforms are typically found in human and animal faeces.
C The presence of E.coli in a water sample means the water is safe to drink.
D The absence of E.coli in a water sample means the water is safe to drink.
A is false. E.coli is a type of bacteria, not a type of virus.
B is true. Faecal coliforms are found in faeces.
C is false. If a water sample is positive for E.coli this indicates faecal contamination, which means it is likely that pathogens are present in the water.
D is also false. The absence of E.coli indicates the water is not contaminated with bacteria of faecal origin but it does not mean it is safe to drink because the water may contain other pathogens.
SAQ 16.2 (tests Learning Outcome 16.2)
In a village there is a protected dug well. The water is treated frequently by chlorine and contamination is avoided. However, you hear that there are several cases of diarrhoea in children. Where would you suspect the water could possibly be recontaminated and what would you do?
You would have to do a sanitary survey to check the possible reasons for the childhood diarrhoea. This would include checking how the water is handled because it may be exposed to recontamination after it is collected from the protected well. Pots and buckets used for collection and storage should be checked to see if they are left open or not. If they are open, and people dip smaller containers into them, there is greater chance of recontamination. A jerrycan is preferable because it has a small opening that cannot be used for dipping. The cleanliness of the containers may be poor because of improper washing or the container may be used to collect both unclean and clean water. You may need to educate the families concerned about good hygiene and the proper handling of water.
SAQ 16.3 (tests Learning Outcome 16.3)
Suppose you have a joint plan with environmental health experts to assess the quality of water from a well. What tests would you do?
Together with the environmental health experts you would conduct tests to measure the colour, taste and odour. You may test pH and for certain chemicals such as nitrate, fluoride and chloride, using portable water field test kits where available. You might also test turbidity (suspended solids). Water analysis would include microbiological tests as well as chemical tests. To do this a water sample would need to be taken and sent to a central laboratory for E.coli assessment and other microbiological tests.
SAQ 16.4 (tests Learning Outcome 16.3)
The people in Agita village have two possible water sources available to them – a protected well and a river. Water quality surveys were undertaken by you and environmental health experts. The results indicate that the river water is highly contaminated with pathogenic microorganisms, but it has a good taste. The well water is tasteless but is not contaminated with pathogenic microorganisms. How would you explain to the villagers that they should use water from the well?
You should tell the villagers that the river water is contaminated with pathogens and will cause waterborne diseases. Without any treatment, the surface water should not be used for drinking and domestic purposes. The water from the well may not taste so nice but it is safer to drink and use for domestic purposes. You will need to advise them that the tests reveal more about water quality than taste does.
SAQ 16.5 (tests Learning Outcome 16.4)
You are about to set off from your Health Post for a neighbouring village to conduct a sanitary survey of a protected spring. What would you take with you? Name four things you will be looking for during your survey.
You would need to take an appropriate checklist of questions to ensure that you survey thoroughly and don’t forget anything. You will also need a notebook and pen or pencil to record all the information you collect. Important things to look for include the location of any latrines or other possible sources of contamination relative to the spring, a sound fence, the condition of the concrete/stone box that protects the spring, the presence of a diversion ditch and any other defect in its construction that could affect the water quality. Your answer could include any four of these or related issues.
Summary of Study Session 16