Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Describe the functions of drainage, plumbing, and sanitation systems.
• Explain different types of pipes and fittings used in South Africa.
• Sketch basic layouts of water supply and wastewater systems.
• Define key plumbing and sanitation terminology.
• Discuss the importance of proper sanitation for public health.

Lesson summary

This week, we delve into the crucial area of drainage, plumbing, and sanitation systems within buildings. These systems are fundamental to public health, safety, and the overall functionality of any structure. Understanding these principles is particularly relevant in the South African context, where access to clean water and effective sanitation remains a significant challenge, especially in informal settlements and rural areas. Poorly designed or maintained systems can lead to waterborne diseases, environmental pollution, and structural damage to buildings.

Lesson notes

2.1 The Importance of Water Supply and Drainage: Water supply systems deliver potable (drinkable) water to buildings for various uses, including drinking, washing, cooking, and sanitation. Drainage systems, conversely, remove wastewater (sewage and greywater) from buildings, preventing contamination and maintaining hygiene. In South Africa, ensuring access to clean and safe water while effectively managing wastewater is vital for public health and environmental sustainability. 2.2 Types of Pipes and Fittings: Different materials are used for pipes and fittings based on their properties, cost, and suitability for specific applications. Let's examine the most common ones used in South Africa: uPVC (Unplasticized Polyvinyl Chloride): Description: A rigid plastic widely used for cold water supply and drainage.

Advantages: Lightweight, corrosion-resistant, relatively inexpensive, easy to install.

Disadvantages: Low resistance to high temperatures (not suitable for hot water), can become brittle over time, prone to damage from direct sunlight if not UV stabilized.

Application: Cold water mains, drainage pipes (sewage and stormwater). Local

Example: A uPVC pipe is a cost-effective and easily accessible choice for water supply in a RDP house.

HDPE (High-Density Polyethylene): Description: A flexible plastic commonly used for water mains and gas pipes.

Advantages: Excellent flexibility, high impact resistance, good chemical resistance, can be joined using fusion welding (creating leak-proof joints).

Disadvantages: More expensive than uPVC, requires specialized welding equipment for jointing.

Application: Underground water mains, gas pipelines, irrigation systems. Local

Example: HDPE pipes are often used for water distribution in large-scale agricultural projects in the Western Cape.

Copper: Description: A metal used for both hot and cold water supply.

Advantages: High resistance to corrosion, good heat conductivity (suitable for hot water), durable, recyclable.

Disadvantages: More expensive than plastic pipes, susceptible to theft (a significant concern in some areas of South Africa), can corrode in highly acidic water.

Application: Hot and cold water pipes, central heating systems. Local

Example: Copper pipes are often used in high-end residential buildings in affluent areas, offering durability and reliability.

However, due to theft risks, they are being replaced by other materials in many new constructions.

Galvanized Steel: Description: Steel coated with zinc to prevent corrosion.

Advantages: Strong, relatively inexpensive (compared to copper), resistant to physical damage.

Disadvantages: Prone to corrosion over time (especially in acidic soils), heavy, difficult to install.

Application: Older water supply systems, industrial applications. Local

Example: Galvanized steel pipes are often found in older houses built before the widespread use of plastics.

PPR (Polypropylene Random Copolymer): Description: A type of plastic pipe, resistant to high temperatures and chemicals.

Advantages: Suitable for hot and cold water supply, durable, lightweight, corrosion resistant, can be joined by heat fusion.

Disadvantages: Expansion rate higher than copper pipes, susceptible to UV degradation Application: Hot and Cold water pipes, potable water systems. Local

Example: PPR is becoming increasingly popular in new housing developments and renovations for its ability to handle both hot and cold water and its relatively easy installation process.

Fittings: Fittings are used to connect pipes and change their direction. Common examples include elbows (45° and 90°), tees, couplings, reducers, and unions. These fittings come in various materials to match the pipes being used. 2.3 Basic System Layouts: Domestic Water Supply System: This system typically consists of a water meter (provided by the municipality), a main water line, branching pipes supplying water to various fixtures (taps, showers, toilets), and a geyser (water heater) for hot water. Pressure-reducing valves might be installed to regulate water pressure. Backflow preventers are also important to stop contaminated water from re-entering the municipal supply.

Wastewater Drainage System: This system includes waste pipes from fixtures, traps (U-shaped bends that prevent sewer gases from entering the building), vent pipes (allowing air to enter the system and prevent siphoning of traps), and a main drain line that connects to the municipal sewer system or a septic tank. Soil pipes carry waste from toilets, while waste pipes carry greywater from sinks and showers. 2.4 Terminology: Potable Water: Water that is safe for human consumption.

Greywater: Wastewater from sinks, showers, and washing machines (excluding toilet waste).

Sewage: Wastewater containing human waste and toilet paper (also called blackwater).

Trap: A U-shaped fitting in a drainpipe that holds water to prevent sewer gases from entering the building.