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Study Session 1  Introduction to Water Supply


Water is one of the essential requirements for life. All living things need water for their survival. Water is used for a variety of purposes, including drinking, food preparation, irrigation and manufacturing. Although water covers more than 70% of the Earth’s surface, less than 1% of that resource is available as fresh water – and this is not evenly distributed throughout the world. More than one billion people (one thousand million) worldwide, mostly in developing countries, lack safe drinking water. Apart from the scarcity of water, there are many other challenges in providing a safe, adequate and reliable water supply in many parts of the world.

In this study session, you will learn about the different uses of water, how water gets to the inhabitants of towns and the challenges faced in delivering water to people.

Learning Outcomes for Study Session 1

When you have studied this session, you should be able to:

1.1  Define and use correctly all of the key words printed in bold. (SAQ 1.1)

1.2  List the various ways in which water is used. (SAQ 1.2)

1.3  Describe how water gets to consumers in towns. (SAQ 1.3)

1.4  Identify the challenges involved in providing safe and adequate water for people in Ethiopia. (SAQ 1.4)

1.1  The basic need for water

According to national and international guidelines, the quantity of water available to all people should be 50–100 litres per person per day, or an absolute minimum of 20 litres per person per day (UNDP, 2006). The water must be safe for drinking and other household uses. Drinking water must be free from pathogenic (disease-causing) micro-organisms (tiny living organisms thatyou can see only with a microscope), and free from chemical and physical contaminants that constitute a danger to a person’s health. It must also be free from colour and odour. Water must be within safe physical reach, in or near the house, school or health facility. According to the World Health Organization (WHO) the water source has to be within 1000 m of the home and collection time should not exceed 30 minutes (UNDESA, 2014).

As well as being physically accessible, water should also be reasonably priced and affordable for everyone. Buying water should not reduce a person’s capacity to buy other essential goods. This means that the cost of water must be kept low and essential amounts of water must sometimes be provided free. In some rural communities of Ethiopia water is provided free, typically from a hand pump managed by a local Water Committee. Occasionally, a charge may be levied by the Water Committee. In urban areas, where water is provided by water utilities, people will pay for the water they use.

1.2  The different uses of water

Water is used in many ways: for domestic purposes, in industry, in commercial establishments (such as hotels and restaurants), in farming (for agriculture and animal-rearing), and for emergency uses such as fire-fighting. Note that the quality and quantity of water for each use is different. Water for domestic purposes needs to be of high quality but is used in relatively small amounts, whereas usage in industry or agriculture could cope with water of a lower quality but the demand is much higher in terms of quantity.

1.2.1  Domestic use

  • Can you think of five uses for water in your daily life?

  • You will have your own answer, but I thought of the following: drinking, washing myself, cooking, watering my fruit trees and washing my (very old) car!

We use water in our homes, both indoors and outdoors. Uses include for drinking, food preparation, washing hands, bathing/showering, brushing teeth, toilet flushing (if there is a flush toilet), cleaning, washing clothes and dishes, and watering plants.

Water is essential for the proper functioning of the body. Human beings can live for several days without food, but only three or four days without water. Each person needs to consume about 2–4.5 litres of water per day (depending on the climate and level of activity) for their body to function properly. (In the next study session you will look at how the body uses water.) In all, each of us needs 30–40 litres of water for domestic purposes, including drinking, food preparation, cooking and washing (WHO, 1997).

The quality of water required for domestic use has to be high, to safeguard health. Piped water supplies in towns and cities that come from well-operated drinking water treatment plants should be safe to drink. For non-domestic purposes, water does not have to be of such high quality and other sources may be appropriate. This is the case at Haramaya University’s Harar Campus, in Misraq Hararghe, Oromia, where students use water from two shallow wells for bathing and washing their clothes, and water supplied by the town’s drinking water treatment plant for drinking and cooking purposes.

1.2.2  Irrigation

About 70% of water used globally is in irrigation. In Ethiopia, the total area under irrigation is increasing and irrigation channels like the one shown in Figure 1.1 can be seen in some parts of the country. Spray irrigation, where pressurised water is sprayed over plants to feed them, is often used on large farms (Figure 1.2), but greater efficiency of water use can be achieved by drip-feed irrigation systems (Figure 1.3). In drip-feed irrigation, water is fed to the roots of plants through narrow pipes dripping water onto the soil surface near the base of the plant. This takes the water directly to the growing crops and reduces losses by evaporation.

Figure 1.1  An irrigation channel in Ethiopia.
Figure 1.2  Spray irrigation in a sugar cane plantation in the Finchaa Valley, Oromia Region.
Figure 1.3  A drip-feed irrigation system. Black plastic pipes run alongside the small plants, providing each of them with water.

1.2.3  Industrial use

In many industries water is essential. Some industries use piped water supplied from water treatment plants while others draw the water themselves from underground sources and treat it on site for use. The water may be used either as part of the production process or as an ingredient, where water is one of the components of the product, for example in a soft-drink plant (Figure 1.4). In the production process, it can be used for cooling, washing, diluting, boiling or cooking, transportation of raw materials (for example, moving potatoes in a food factory), and as a cleaning agent.

Figure 1.4  A soft-drink production plant in Ethiopia.

1.2.4  Mining use

Mining activities use huge amounts of water in processing ore to extract minerals. In Ethiopia, mining for gold and other valuable metals is an increasingly important part of the national economy (Figure 1.5) and would not be possible without the use of water.

Figure 1.5 Mining for gold in Okote, Oromia Region.

1.2.5  Use in power generation

The rivers of Ethiopia have enormous potential for generating hydroelectric power (HEP). HEP uses the energy from moving water and converts this to electrical energy. The development of HEP has transformed energy supply in recent years and more schemes are under construction or planned. However, it is important to realise that in HEP the water is not ‘used’ in the sense of being consumed, because after passing through the HEP plant the water continues on its path in a river channel.

Another process under development in the Rift Valley area of Ethiopia is the use of geothermal energy, in which energy is derived from the heat of the Earth. This process involves drilling down into hot layers of underground rock and using this heat to convert water into steam, which is then used to drive generators to produce electricity. Figure 1.6 shows a geothermal electricity generation plant.

Figure 1.6  A geothermal power plant.

1.2.6 Aquacultural use

Water can also be used in aquaculture, which is the farming of aquatic organisms such as fish, crustaceans and molluscs for food. Fish farming (Figure 1.7) obviously needs water for the fish to live in! In this case,water is used to hatch fish eggs under controlled conditions, and the fish are grown to maturity in tanks or ponds, before being sold for food. Although not currently practised in Ethiopia, the business potential for aquaculture has been recognised and it may be introduced in the future (Rothuis et al., 2012).

Figure 1.7 A fish farm.

1.2.7 Recreational use

Water plays an important role in recreational activities and here again it is not consumed in the process of its use. Boat trips are popular on many of Ethiopia’s lakes and several resorts have been built on their shores. An example is shown in Figure 1.8.

Figure 1.8  A resort at Babogaya Lake near Bishoftu.

1.3  How water gets to people living in towns

We obtain the water we use from three basic sources: groundwater, surface water and rainwater. Groundwater includes all water that is found underground within the rocks. Surface water means water in rivers, lakes, pools and ponds. Rainwater replenishes both groundwater and surface water, and can also be collected directly. These sources are discussed further in Study Session 3. For the purpose of this introductory study session, here is a brief summary.

1.3.1  Urban water sources

In urban areas, the water supply originates from one of the following basic sources:

  • A spring (a point where groundwater emerges at the surface of the ground), from where the water can be piped to consumers. A spring may flow throughout the year or only at times.
  • A well or borehole. These may supply individual residences or a large number of houses where the water is delivered through a network of pipes. In addition to this, institutions such as schools, health facilities, religious establishments, small commercial enterprises and industries may have their own water supply system from hand-dug or deep wells.
  • Surface water from rivers and lakes, which may be abstracted directly or stored in a reservoir created by building a dam across a river. Abstraction means taking water from the source so that it can be used.

Springs and wells are considered improved sources of water if they are constructed and used in such a way that they adequately protect the water from contamination, especially by faecal matter. Spring or well water is generally used with minimal or no treatment. Surface water is an unimproved source and will require some form of treatment before it is safe to use for drinking. In larger towns and cities, surface water is treated in a water treatment plant before being distributed to consumers. The term raw water is used to describe the water before it is treated. Figure 1.9 shows the plant at Legedadi that supplies water to residents of Addis Ababa. (You will learn about water treatment in Study Session 5.)

Figure 1.9  The drinking water treatment plant in Legedadi.

1.3.2  Delivering the water to consumers

In towns and cities with a water treatment plant, the treated water is taken to consumers through a network of pipes and reservoirs. Figure 1.10 is a diagram of a water distribution network of this type. (Water distribution networks are discussed in more detail in Study Session 8.)

Figure 1.10  A simple water distribution network.

From Figure 1.10 you can see that transmission mains convey the treated water from a treatment works to service reservoirs (Figure 1.11). These reservoirs balance the fluctuating demands of users against the steady output of the treatment works and also serve as a back-up supply should there be a breakdown at the plant.

Figure 1.11  A concrete service reservoir in Janemeda, Addis Ababa.
  • Why do you think demand for water will fluctuate?

  • People generally use more water in the mornings and evenings when they are washing and cooking. Usage during the night while people are asleep will be much lower.

The capacity of the service reservoirs should be at least 36 hours of the water demand in the area they serve. The service reservoirs are usually made of concrete and often, for reasons of economy and appearance, are sunk wholly or partly below ground level. The reservoir needs to be positioned on high ground to provide an adequate flow by gravity to the distribution area, and to create sufficient pressure to raise the water to the top of buildings. In flat areas, water towers (Figure 1.12) may be used in place of service reservoirs. (A water tower is an elevated structure supporting a water tank. Water is pumped up into the tank, which is constructed at a height sufficient to pressurise the water supply system so that water can be distributed by gravity).

Figure 1.12  A water tower in Addis Ababa.

From the service reservoir, the water is taken by distribution mains to different areas. Distribution mains consist of a network of pipes of various sizes laid beneath the road, footpaths or verges. The water is taken to houses and other premises where water is needed. Here, the water goes to a tank in the roof-space or on the roof so that it is able to flow by gravity to all the taps in the establishment. The taps can be within a house or outside (Figures 1.13(a) and 1.13(b)). Sometimes water can be delivered by a tanker that pumps the water to the household’s water tank, or people collect water from the tanker using jerrycans. In urban areas, public water points are a very common water source for many people (Figure 1.13(c)).

Figure 1.13(a)  A tap inside a house.
Figure 1.13(b)  A tap located in a yard and shared by several households.
Figure 1.13(c)  A public water point at Adi Sibhat, Tigray.

Continuity of supply is important so that people can be confident that water will be available when they need it. Where the supply of water is not continuous, many households have storage tanks to accumulate water for use when the supply is off. It is important to check the cleanliness of the storage tank regularly, and to clean and disinfect it as necessary.

In the case of seasonal discontinuity, users may be forced to obtain water from alternative sources, which are often of inferior quality and far away. As a consequence, the health of people will be put at risk by poor water quality and low quantity. In addition, considerable time and effort are spent on collecting water.

  • In many towns and cities in Ethiopia, if you turn on a water tap at any random time it is quite likely that you will not get any water. Why do you think this happens?

  • It may be because demand for water exceeds the supply available at that time. It can also happen due to a power failure or poor maintenance.

1.4  The challenges for urban water supply in Ethiopia

Ethiopia has plenty of water resources but the available water is not distributed evenly across the country and the amount varies with seasons and years. The challenge in any situation is to maintain a year-round supply that is adequate to meet people’s needs. To ensure that supply meets demand the source of the water must be carefully chosen, taking into account present and future demand for water, and the costs. The cost of water supplies is heavily influenced by the distance of reliable water sources from towns. The challenge for many towns is finding nearby water sources.

Planning for present and future demand has to consider population growth. The demand for water is increasing in cities and towns due to an ever-growing population and the migration of people from rural areas to towns in search of jobs and a better life. There are also increasing demands from industrial and commercial development. The quantity of water required for domestic use depends not only on the number of people but also on their habits and culture, and on how accessible the water is. On average, Ethiopians in urban areas use only about 15 litres of water a day for their needs (MoH, 2001; Ali and Terfa, 2012).

  • How much water do we really need?

  • From Section 1.2.1 you will recall that, according to the WHO, each of us needs 30–40 litres of water a day for all domestic purposes.

Why is there such a difference between the WHO estimate and the daily water consumption per person in Ethiopian towns? The shortfall is perhaps due to the shortage of private water taps, which means that people have to collect water from public taps. If people have a piped water supply in their home they are likely to wash and bathe more frequently, and some may have water-using appliances like washing machines. As water supply systems improve and access increases, the consumption of water will increase also. It is therefore important for water supply planners to consider the expected changes in society and in living standards. Planning of water supply projects should also consider the water requirements of schools, hospitals and other health facilities, churches and mosques, hotels, public washrooms, and other community facilities.

The government of Ethiopia has set targets of 100% coverage of safe water supply in urban areas and 98% coverage in rural areas. These targets originated from the Universal Access Plan of 2005 and the Growth and Transformation Plan of 2010, and have been adopted by the One WASH National Programme (OWNP), which is being implemented with major funding from government and international donors (FDRE, 2013). The planning criteria for water supply coverage in the OWNP are:

  • rural water supply: 15 litres/person/day, within 1.5 km radius
  • urban water supply: 20 litres/person/day, within 0.5 km radius (FDRE, 2013).

As you can see, these figures are still below the WHO recommendation and are more than current usage, indicating the scale of the challenge ahead. The targets for Ethiopia are that 4.4 million urban inhabitants and 26.6 million rural inhabitants, nearly 30,000 schools, and more than 7500 health posts/centres will gain access to safe drinking water (FDRE, 2013). Progress towards meeting these targets is described in Study Session 3.

At the beginning of this study session you read that water supply must be accessible and affordable. It is important that affordability extends to all sectors of society, including vulnerable people. Vulnerable groups include low-income households and households with many young children, older people, disabled people and people with long-term illness such as HIV/AIDS. Equitable access to water supply for all these groups should also be taken into consideration, especially when considering the cost of water as these vulnerable people usually have low income.

There are still many challenges ahead but the following changes will all contribute to future success:

  • an increase in funds for the expansion of water supply services to satisfy the demand of growing populations, particularly in small towns
  • a reduction in bureaucracy to facilitate the spending of funds that are committed (currently only around 60% of budgeted finances are actually spent)
  • a reduction in the turnover of personnel, and an increase in human resource capacity and expertise at different levels
  • better coordination between the different stakeholders (for instance, there is lack of coordination between the water sector, telecommunication department and the road authority; because of this, water pipes are frequently damaged during activities such as laying down telephone and internet lines, and during road construction)
  • the presence of more experts to monitor sector performance at all levels
  • better information management systems, giving early warning of requirements.

Summary of Study Session 1

In Study Session 1, you have learned that:

  1. Water is essential for life. Drinking water must be safe, of adequate quantity, accessible and affordable.
  2. Water has several uses of which the most important are for personal consumption and cleanliness, for irrigation, and for industry. The quality of water acceptable for the various uses can be different.
  3. Urban water supply may originate from springs, wells or surface water. Water from springs and wells is generally used without any treatment, while surface water needs treatment before it is safe to drink.
  4. In an urban water distribution network, transmission mains take water from water treatment plants to service reservoirs. Service reservoirs are located on high ground so that water flows by gravity through distribution mains to the water consumers. Where there is no high ground, water towers are constructed and used.
  5. Water supply planning must take account of present and future water demand by people, and by industrial and commercial development. Domestic use is likely to increase as living standards improve. Planning also needs to consider the needs of schools, health facilities and other institutions.
  6. There are many challenges facing urban water supply in Ethiopia and several factors that can contribute to overcoming them, including increased funding, reduced bureaucracy, capacity building, better coordination between the stakeholders involved, and better information management.

Self-Assessment Questions (SAQs) for Study Session 1

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions.

SAQ 1.1 (tests Learning Outcome 1.1)

Match the following words to their correct definitions.

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

  1. improved water sources

  2. raw water

  3. drip-feed irrigation

  4. hydroelectric power

  5. distribution mains

  6. aquaculture

  7. spring

  8. surface water

  9. transmission mains

  10. spray irrigation

  11. groundwater

  12. pathogenic micro-organisms

  13. geothermal energy

  14. water tower

  15. abstraction

  16. service reservoirs

  • derived from the heat of the earth

  • b.stores of water that balance the fluctuating water demands of users against the steady output of the water treatment plant

  • c.pipes that take water from a service reservoir to different areas

  • d.micro-organisms that cause disease

  • e.power produced by harnessing the energy of moving water

  • f.a form of irrigation where water is sprayed over plants

  • g.the taking of water from a source

  • h.the farming of aquatic organisms

  • i.water that has not yet been treated

  • j.water from rivers, lakes, pools and ponds

  • k.a form of irrigation where water is put at the base of a plant, using narrow pipes

  • l.a point where water flows out of the ground

  • m.water sources that are protected from contamination, especially by faecal matter

  • n.water that is underground

  • elevated structure that has a water tank to supply drinking water by gravity

  • p.pipes that take treated water from a treatment plant to service reservoirs

The correct answers are:
  • 1 = m
  • 2 = i
  • 3 = k
  • 4 = e
  • 5 = c
  • 6 = h
  • 7 = l
  • 8 = j
  • 9 = p
  • 10 = f
  • 11 = n
  • 12 = d
  • 13 = a
  • 14 = o
  • 15 = g
  • 16 = b

SAQ 1.2 (tests Learning Outcome 1.2)

Imagine you are in a quiz show on television and the host says, ‘For 1000 birr can you write down six non-domestic uses of water in two minutes?’

What would you write?


If in two minutes you wrote ‘irrigation, industry, mining, power generation, aquaculture, recreation’, you would be richer by 1000 Birr!

SAQ 1.3 (tests Learning Outcomes 1.1 and 1.3)

The following statements relate to water supply from a drinking water treatment plant in a large town. Fill in the blanks, using the words given below, and then put the statements in the right order.

distribution mains; river; cut in water supply; service reservoirs; lake; safe for human consumption; transmission mains.

  • a.Water is taken from the treatment plant to ………………………… by …………………………
  • b.Raw water is abstracted from a ………………………… or a …………………………
  • c.Water is stored at home in case of a …………………………
  • d.Water is taken from the service reservoirs to consumers by …………………………
  • e.Water undergoes treatment so that it is …………………………


The completed statements, in the correct order, are as follows:

b.  Raw water is abstracted from a river or a lake.

e.  Water undergoes treatment so that it is safe for human consumption.

a.  Water is taken from the treatment plant to service reservoirs by transmission mains.

d.  Water is taken from the service reservoirs to consumers by distribution mains.

c.  Water is stored at home in case of a cut in water supply.

SAQ 1.4 (tests Learning Outcome 1.4)

Which of the following would not help in improving the water supply situation in Ethiopia? Give your reasons.

  • Planning for expansion of towns and industry.
  • Ensuring that the local water office always has new members of staff so that they are enthusiastic.
  • More money being devoted to the water sector.
  • Having more qualified people in the water industry.
  • Reducing the interaction between the different organisations involved so that less time is wasted.
  • Having better monitoring of performance and requirements in the water sector.


The following would not help:

Ensuring that the local water office always has new members of staff so that they are enthusiastic. It is better to have staff who stay on in their jobs as they will gain experience and manage the system well.

Reducing the interaction between the different organisations involved so that less time is wasted. Interaction between stakeholders is important because they need to coordinate their activities with each other.