Plumbing: Water Supply and Drainage Systems — CSEC Building Technology

Plumbing installs and maintains the pipes that supply clean water and remove waste water from a building.

Water supply

• Water is supplied from the mains or a source, sometimes via a storage tank that maintains supply and pressure, then through supply pipes to taps and appliances.
• Pipes are commonly PVC/plastic or copper.
• Valves and taps control or stop the flow of water.
• Backflow prevention stops dirty water from re-entering and contaminating the clean supply.

Drainage

• Drainage pipes carry away waste water and are laid with a slight slope (fall) so waste flows away by gravity and does not block.
• A trap (U-bend) beneath sinks and toilets holds a water seal that stops foul drain gases entering the building.
• The soil pipe carries waste from toilets to the sewer or septic system.

Joining pipes

Pipes are joined by soldering (copper), solvent-welding (plastic) or threaded fittings, ensuring watertight connections.

Method (cold supply path)

Mains/source → storage tank → supply pipes → tap (outlet).

Exam tips

• A trap (U-bend) provides a water seal that blocks drain gases.
• Drains need a slope (fall) so waste flows by gravity.
• Valves/taps control flow; backflow prevention protects the clean supply.
• The soil pipe carries toilet waste to the sewer.