Lesson Notes By Weeks and Term - Junior Secondary School 3

TERM: 2ND TERM

SUBJECT: BASIC TECH

CLASS: JSS 3

Reference Materials

• NERDC, INTRODUCTORY TECHNOLOGY FOR JSS, BOOK 3
• EVANS, INTRODUCTORY TECHNOLOGY FOR JSS, BOOK 3

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WEEK 7

TOPIC: RURAL AND URBAN WATER SUPPLY

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CONTENT

• Sources of water�
• Quality of water
• Water purification
• Transmission and distribution of water system

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SOURCES OF WATER

There are two main sources of water supply for rural and urban areas the surface sources and the underground sources

Sources of water are broadly classified as under ground sources and surface sources.�

Evaluation�

1. State� and explain two main sources of water

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The surface sources are the lakes, rivers, upland surface water while the underground water includes the springs and wells.

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SURFACE WATER: It originates from rainfall. It is a mixture of surface run off and ground water. This includes the rainwater collected directly from the roof, from the rivers, ponds and lakes and runs off from natural catchments into the natural or artificial lakes.

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Rain water can be collected from the roofs of the building into the storage drums and tanks or buckets via overhanging collection trough. Rain water is the softest natural water, although it can be contaminated if the collecting surfaces are not well maintained

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THE UNDERGROUND WATER: It is that portion of rainfall, which has percolated into the earth to form underground deposits. Examples include walls and springs.

Spring water is the water that has traveled as a result of its geological conditions. it is not different from wells.

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Underground water is practical and safe in nature due to the following reasons:

• It is ,in most cases, free from diseases.(filtration into the ground)
• It may taken without further treatment.
• It is practical to dig at any convenient locations.
• It serves the purpose of direct water supply.�

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Evaluation�

1. State two examples of surface� water
2. State two examples of underground water

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QUALITY OF WATER

Ordinary raw water contains micro-organisms and dissolved substances which are a health hazard, and must therefore be removed by treating the water.

Water meant for human consumption must:

1. Be free from chemical substances and micro-organisms
2. It must not be turbid i.e. cloudy
3. It must be colourless, tasteless and odourless.

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WATER PURIFICATION

The process by which water could be treated involves any of the following methods:

1. Filtration
2. Clarification
3. Aeration
4. Disinfect ion

Filtration: Urban water supply is filtered to remove particulate matter.

Clarification: This done to remove the suspended materials so that the water becomes clear.

Aeration: To remove various dissolved gases (methane, hydrogen sulphide, carbon dioxide etc)

Disinfect ion: This is the process of using chlorine to destroy undesirable organism in water, to improve coagulation of water, to control the odours in water and sludge in the purification chamber and to eliminate hydrogen sulphide in water.

Evaluation�

1. State the qualities of clean water.
2. State and explain 4 processes of water purification�

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TRANSMISSION AND DISTRIBUTION SYSTEM

Rural Water Supply is mainly from rivers and shallow wells. Water from the well can be brought to the surface manually or with the aid of a windless, hand pump or motorized pump.

There are two main pumps for pumping water- reciprocating plunger pump and the rotary pump. When the well is not the too deep (i.e.5m) the pump can be installed at the ground level. For deep wells, the pump is lowered down into the well.

Household treatment of water can be accomplished by boiling water and/or using water filter of appropriate grade (V or N or W)

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Urban Water Supply: An urban water supply scheme (WSS) involves a collection or water impounding system (dam), a purification system, a transmission and distribution system.

The treatment of water involves the following processes: aeration, clarification, filtration and disinfection.

Pipelines are laid to convey treated water to the distribution reservoir, and the distribution lines to various service outlets.

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The clear and pure water from the treatment plant is pumped through pipeline into the city reservoir for distribution to various service outlets���

Evaluation�

1. Briefly describe the transmission and distribution of water the following:

1. rural areas
2. urban areas

DISTRIBUTION RESERVOIR

Distribution reservoirs help to store excess water during the period of low demand and discharge it during the period of high demand. They are usually centrally located on an elevation to ensure distribution by gravity i.e. no pumping.����

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This helps to maintain a regular water supply to meet the hourly variation of water demand. The reservoirs are sited on high position above the ground at least 10m higher than any storey building in that area. This is to ensure distribution by gravity.

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Evaluation�

1. State the classification the sources of water.
2. Mention 3 qualities of a good water�
3. Mention the water purification processes

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Reading Assignment

Read RURAL AND URBAN WATER SUPPLY

Reference Materials���

1. EVANS, Introductory Technology for JSS, book 3, pages 158 - 170

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Weekend Assignment�

1. There are ____ main sources of water supply for rural and urban areas. A) one (b) two (c) three (d) four
2. The following are examples surface sources except (a) lakes (b)rivers (c) upland surface water (d) spring
3. Which of the following is a/an example of the underground water? (a) springs (b) lakes (c) rivers (d) upland surface water
4. The process by which water could be treated involves any of the following methods except (a) Filtration (b) Clarification (c) Aeration and Disinfect ion (d) Chromatography
5. Which of the helps to store excess water during the period of low demand and discharge it during the period of high demand? (a) Distribution reservoirs (b) filter tank (c) sedimentation tank (d) overhead tank

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Theory���

1. State two sources of water� and give 2 examples each
2. Briefly describe the transmission and distribution of water the following:

• rural areas
• urban areas