Self-Assessment Questions (SAQs) for Study Session 17

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 17.1 (tests Learning Outcome 17.1)

Match the definitions with the corresponding words below.

Using the following two lists, match each numbered item with the correct letter.

  1. A foreign component in a substance

  2. High levels of plant nutrients in water

  3. The source of pollutants is visible at time of discharge

  4. Diffuse source of pollution

  • a.Contaminant

  • b.Point source pollution

  • c.Eutrophication

  • d.Non-point source pollution

The correct answers are:
  • 1 = a
  • 2 = c
  • 3 = b
  • 4 = d

SAQ 17.2 (tests Learning Outcome 17.2)

In the village of Felashit, there are two dug wells. Some villagers fetch water from the eastern well and another group fetches water from the well dug on the western part of the village. The residents in the eastern part of the village are suffering from an outbreak of diarrhoea. What might be the possible reasons for this?


Assuming there were no other differences to consider than their respective sources of water, it would seem likely that the eastern well has become contaminated. The possible sources may be point sources from a latrine, if there is one located above the dug well or from an overflow of the latrine into the dug well. Possible non-point sources might be open defecation around the village causing contamination of the well after rain. Further investigation would be needed to identify the cause for certain.

SAQ 17.3 (tests Learning Outcome 17.3)

Suppose you are working in a village and the community members want to know how they should protect their water source from pollution. What pollution control techniques would you tell them about?


Your answer will depend on the local situation but the same general rules will apply anywhere. You should advise them to be aware of the importance of proper disposal of human excreta, which means avoiding open defecation and constructing latrines that are at least 15 m away from water sources and at a lower level; appropriate disposal of animal wastes; appropriate disposal of solid waste; and the possibility of pollution from agricultural activities such as spreading fertiliser. In some locations there may also be potential hazards from industry, roads and other sources of pollution.

SAQ 17.4 (tests Learning Outcome 17.4)

Imagine that you have been asked to take water samples from the two wells in Felashit village for chemical and microbiological analysis. What would you do to ensure that accurate samples were taken?


It would be important to ensure there was no contamination of the samples during or after sampling and that they were a representative sample of the water in the wells. The sampling bottles and their stoppers must be sterilised. The sample bottles for the two wells would need to be clearly labelled so that there was no danger of confusion between them. The sample should be taken by weighting the bottle and lowering it on a string into the well, lowering it below the surface of the water but not hitting the bottom, waiting until it is filled, then raising the bottle and capping it immediately.

Summary of Study Session 17