Fiche de révision : Building Utilities and Waste Systems

📋 Course Outline

1. Utilities and building services
2. Water supply systems
3. Cold and hot water supply
4. Sanitary appliances
5. Drainage and sewer systems
6. Solid waste collection systems
7. Waste disposal methods

📖 1. Utilities and building services

🔑 Key Concepts & Definitions

• Utilities : Utilities are infrastructure services provided to consumers, often treated as public services crucial to society’s normal functioning.
• Potable water supply : Potable water supply is the provision of safe drinking and hygienic water for building needs and daily activities.
• Sanitary system : A sanitary system is the set of arrangements that supplies and uses water fixtures designed for hygiene in buildings.
• Waste management : Waste management covers collecting solid waste and disposing of it in ways intended to be hygienic and environmentally controlled.

📝 Essential Points

• Utilities generally include electricity, gas, water, sewage, and communications services.
• Potable water supports personal hygiene, cooking, drinking, cleaning, gardening, and industrial processes.
• After entering a building, potable water is divided into cold water and hot water.
• Sanitary/dried drainage systems connect building sanitary functions to drainage and, ultimately, treatment or disposal flows.

💡 Memory Hook

Potable = Personal + Cooking + Cleaning + Gardening + Industry.

📖 2. Water supply systems

🔑 Key Concepts & Definitions

• Water supply system : A water supply system is the arrangement that brings water into a building, stores it when needed, and distributes it to fixtures.
• Storage and distribution : Storage and distribution describe how stored water is supplied to different floors and outlets under gravity or pressure.
• Connection to water main : Connection to water main is the link between building pipes and the municipal distribution pipe system, using valves for control.
• Pipe diameter for domestic : Domestic pipe diameter is the specified size used for carrying water within a dwelling to supply fixtures.

📝 Essential Points

• For domestic use, pipe diameter is given as 20 mm, while main distribution pipe diameter is given as 12 mm.
• In high-rise or high-ground buildings with low pressure, pumping equipment and extra water cisterns may be needed.
• Kitchen sink cooking water should use direct supply from the mains to ensure cleanliness and freshness.
• Building supply methods can include direct and indirect systems depending on the need for storage and pressure conditions.

💡 Memory Hook

20 mm for domestic, 12 mm for main: domestic needs thicker local runs.

📖 3. Cold and hot water supply

🔑 Key Concepts & Definitions

• Cold water direct system : A cold water direct system supplies cold water directly from the mains distribution pipes to fixtures without a storage tank.
• Cold water indirect system : A cold water indirect system uses a storage tank fed by the distribution main and supplies different floors by gravity except the kitchen sink.
• Hot water central boiler system : A hot water central boiler system heats water centrally for supply to hot water cylinders and distribution.
• Hot water localized heating cylinder : A localized heating cylinder heats water on-site for hot water supply when not using a central boiler arrangement.

📝 Essential Points

• Cold water direct system has no storage tank and can maintain freshness, cleanliness, and high pressure with less cost due to fewer pipes.
• Cold water direct system fails if the main distribution pipe is under maintenance and requires good, durable distribution pipes to handle higher pressure.
• Cold water indirect system provides reserved storage up to 12–24 hrs during main interruption and can give constant pressure in the distribution system.
• Hot water systems use copper or stainless conduct due to higher temperature and expansion valve needs.
• Central boiler use is indicated for large hot-water quantity or long heating duration, with enough boiler space for gas/coal-fired heating.

💡 Memory Hook

Direct: Fresh NOW, but fragile to main maintenance; Indirect: Storage buffer 12–24 hrs, but risks tank-related contamination.

📖 4. Sanitary appliances

🔑 Key Concepts & Definitions

• Sanitary appliances : Sanitary appliances are building fixtures required for specialized hygienic functions and can be supplied from mains or cold/hot storage vessels.
• Back siphonage prevention : Back siphonage prevention refers to tap design aimed at stopping foul-water from flowing back into the supply pipe.
• Minimum water seal : Minimum water seal is the required depth of water trap seal in a water closet to help block foul gases.
• Flushing cistern : A flushing cistern is the tank that provides water for flushing sanitary fixtures, commonly with a stated capacity and multiple types.

📝 Essential Points

• Taps are designed to prevent back siphonage of foul water into the supply pipe and are made with minimum fouling area.
• Flushing cistern usual capacity is 9 litre, and types include bell-type and disc/piston type.
• A water closet is designed to maintain a 50 mm minimum water seal and higher cistern level gives more effective flush.
• Siphonic water closets are described as more silent and positive than wash down type.
• Bidet is a waste fitting for perineal washing and footbath with hot and cold water mixed to required spray temperature.

💡 Memory Hook

50 mm seal: think “50” as the trap’s foul-gas barrier height.

📖 5. Drainage and sewer systems

🔑 Key Concepts & Definitions

• Sanitary drainage system : A sanitary drainage system conveys wastewater and rainwater away from building sanitary appliances into larger drains and onward treatment.
• One-pipe system : The one-pipe system is an early soil and waste disposal arrangement aimed at reducing labor and material by using fewer pipes.
• Two-pipes system : The two-pipes system is a soil and waste disposal arrangement that requires separate connections to a waste stack for appliances.
• Combined sewers system : A combined sewers system carries multiple types of waste in the same sewer arrangement as indicated in the course diagram set.

📝 Essential Points

• The one-pipe system uses less piping work and is cheaper to install, and it has been used successfully for multi-storey flats.
• For the one-pipe system, discharge pipes are recommended to be fitted inside the building for refurbishment work.
• The two-pipes system is described as the most expensive soil and waste disposal system and needs appliances connected to a separate waste stack.
• Waste appliances such as basin, sink, bidets, and showers connect to a waste stack and soil appliances.
• The course sequence shows rainwater and wastewater conveying from small drain to big drain and onward to a water treatment plant.

💡 Memory Hook

One-pipe = cheaper, fewer pipes; Two-pipes = more cost, separate waste stack.

📖 6. Solid waste collection systems

🔑 Key Concepts & Definitions

• Solid waste : Solid waste is unwanted solid material that must be disposed hygienically without harming the environment.
• Refuse bin : A refuse bin is a collection container used for non-high rise flats where waste is placed into disposable plastic bags for collection.
• Refuse chutes : Refuse chutes are hollow shaft collection routes in high rise flats with inlets on each floor and collection at the bottom.
• Garchey system : A Garchey system is a sealed waste handling layout using a special sink unit, stack pipe, collection chamber, vacuum lorries, and sewer.

📝 Essential Points

• Solid waste sources are categorized as domestic, commercial, and industrial, including examples like food and toxic offensive dangerous items.
• Refuse bin collection for non-high rise flats uses disposable plastic bags placed inside bins for collection.
• Refuse chutes can be configured as chute plus refuse container or chute plus incinerator.
• In refuse chute systems, the top has a ventilation vent, each floor has an inlet hopper, and the bottom has either refuse container or incinerator for ash collection.
• Sink grinders are electrically powered units installed under a kitchen sink that shred food waste into small pieces.

💡 Memory Hook

Chutes for high rise: vent at top, hopper each floor, and container/ash at bottom.

📖 7. Waste disposal methods

🔑 Key Concepts & Definitions

• Waste disposal : Waste disposal is the set of methods used after collection to treat or remove waste without unacceptable hygiene or environmental impact.
• Incinerator : An incinerator is a disposal method that combusts waste to reduce landfill focus and recover energy while controlling emissions and handling ash.
• Controlled landfill : Controlled landfill is a disposal approach described as better than open land dumping while still involving land-based waste placement.
• Wastewater treatment plant : A wastewater treatment plant processes wastewater into an effluent that can return to the water cycle with minimal environmental issues.

📝 Essential Points

• Sea dumping is described as unhygienic and providing environmental risk.
• Open land dumping is described as unhygienic and providing environmental risk.
• Controlled landfill is described as better than open land landfill.
• Incineration includes combusting waste, extracting heat for steam and electricity generation, controlling emissions, and handling ash carefully.
• Recycled plant is described as having high capital but being environmentally friendly with long term profit, and wastewater treatment needs higher capital but is environmentally friendly.

💡 Memory Hook

Four-step incineration: Burn → Steam/Electricity → Emissions control → Ash management.

📊 Synthesis Tables

Cold water: direct vs indirect

⚠️ Common Pitfalls & Confusions

1. Students may mix up direct and indirect cold water rules, especially the exception for kitchen sink in the indirect system.
2. Students often forget the stated pipe diameters (20 mm domestic, 12 mm main) and then cannot justify which runs are which.
3. Students may confuse the 9 litre flushing cistern capacity with the 50 mm minimum water seal requirement for a water closet.
4. Students may treat siphonic water closets as quieter but then choose the wrong alternative description like wash down type.
5. Students may swap categories of solid waste sources (domestic, commercial, industrial) and lose the given example types.
6. Students may think incineration replaces emission monitoring, but the course stresses emissions control and ash management.

✅ Exam Checklist

1. Define utilities and list the broad service types included in utilities as presented in the course.
2. List the key reasons potable water is required in buildings (hygiene, cooking/drinking, cleaning, gardening, manufacturing).
3. Explain how potable water entering a building is divided into cold water and hot water categories.
4. State the given pipe diameters for domestic pipes and main distribution pipes.
5. Choose which cold supply method fits the kitchen sink rule described in the course (direct mains supply).
6. For cold water direct system, state that no storage tank is required and name both an advantage and a disadvantage from the course.
7. For cold water indirect system, state how it supplies different floors and give the 12–24 hrs storage point plus one contamination-related disadvantage.
8. Describe the stated materials and purpose rationale for hot-water conduct and expansion valve use.
9. State when a central boiler is used for hot water and name the listed fuel types for the boiler.
10. For sanitary appliances, state the tap design intent regarding back siphonage and fouling area.
11. State the flushing cistern usual capacity (9 litre) and list the two cistern types named.
12. State the water closet 50 mm minimum water seal requirement and the comparison claim about siphonic vs wash down.
13. Describe the one-pipe system trade-off (fewer pipes/cheaper) and a refurbishment-related recommendation from the course.
14. Describe the two-pipes system as the most expensive option and the requirement to connect appliances to a separate waste stack.