--- title: "Domestic water supply and drainage systems" subject: "Building Technology" chapter: 12 key: "semester_6/building_technology:water-supply-drainage" source: https://www.bctengineer.com/q/semester_6/building_technology/water-supply-drainage site: BCT Engineering --- # Domestic water supply and drainage systems Building Technology · Chapter 12: Other services in building - Asked in: 2070 Chaitra (old course), 4+4 marks - Video: [Water Distribution | System Design and Layout](https://www.youtube.com/watch?v=f2faanH0_Ww) — American Water College - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/building_technology/water-supply-drainage - Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-12 ## Question What is domestic water supply system? Discuss the types of drainage system with necessary figures. ## Short answer A domestic water supply system is the arrangement of pipes, tanks, and pumps bringing water from the main or a source to fixtures at adequate pressure and quality. Drainage system types are combined (one pipe for both sewage and stormwater), separate (two pipes), and partially separate. Inside the building, single-stack, one-pipe, and two-pipe systems are used. ## Answer #### Domestic water supply system It is the arrangement of pipes, tanks, pumps and fittings that brings water from the public main or a private source (well, spring) to the taps, WCs and appliances of a house, in sufficient quantity, at sufficient pressure and of good quality. Typical parts: service connection with meter, underground sump, pump, overhead tank, distribution pipes with valves, and fixtures. ```text Main -> meter -> sump -> pump -> roof tank |-> kitchen, bath, WC ``` Types: direct (up-feed), indirect (down-feed from a tank) and combined. #### Types of drainage system Drainage removes sewage and storm water from the building. 1. **Combined system:** one sewer carries both sewage and storm water. It is cheap and needs only one pipe, but the pipe is large, it overloads in heavy rain, and the treatment plant is overloaded. 2. **Separate system:** sewage in one pipe and storm water in another. More costly, but the pipes are smaller and the treatment works receive only sewage. Best for new areas. 3. **Partially separate system:** a small part of the storm water (from roofs and courtyards) goes into the sewer; the rest goes into separate drains. | Point | Combined | Separate | |---|---|---| | Number of pipes | One | Two | | Cost | Low | Higher | | Treatment load | High in rain | Steady | | Flushing | Good self-cleansing | Needs flushing | ```text Separate system house --soil pipe----> sewer -> treatment roof/yard --rain pipe-> storm drain -> river ``` **Inside the building:** single-stack system (one vented stack for soil and waste), one-pipe system, two-pipe system (separate soil and waste stacks) and the modified one-pipe system. Fixtures have water-seal traps, and inspection chambers are placed at bends and junctions. **Outside:** drains of vitrified clay, concrete or PVC laid to gradients of 1 in 40 to 1 in 100, connecting to the sewer or septic tank. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is a domestic water supply system? A. Pipes, tanks, pumps and fittings that bring water from a main or private source to taps and appliances in sufficient quantity, pressure and quality B. Only the sewer connection C. A rainwater recharge pit D. A fire hydrant Answer: A. It is the arrangement of pipes, tanks, pumps and fittings delivering water to the fixtures of a house. (Key point: Domestic water supply) 2. What is a combined drainage system? A. Two separate pipes for sewage and storm water B. One sewer carries both sewage and storm water C. Only storm water is carried D. Sewage is discharged without a sewer Answer: B. The combined system uses one sewer for both; it is cheap but overloads in rain. (Key point: Combined system) 3. What is an advantage of the separate system? A. It is cheaper because only one pipe is used B. Treatment works receive only sewage and pipes are smaller C. It needs no flushing D. It is self-cleansing Answer: B. Sewage and storm water go in different pipes, so pipes are smaller and the treatment plant gets only sewage, though it costs more. (Key point: Separate system) 4. What is a partially separate system? A. All storm water goes to the sewer B. A small part of storm water (roof and courtyard) enters the sewer and the rest goes in separate drains C. No storm water enters any drain D. Sewage goes to storm drains Answer: B. In the partially separate system only a portion of storm water joins the sewer. (Key point: Partially separate system) ## Related in Building Technology - [Domestic water supply; septic tank and soak pit](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awater-supply-septic-067as) — Building Technology, chapter 12 - [Short note: Water supply and distribution system](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awater-distribution-short) — Building Technology, chapter 12, asked 2× - [Principles of laying out water supply system](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awater-supply-principles) — Building Technology, chapter 12 - [Water supply and sanitation management](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awater-supply-sanitation) — Building Technology, chapter 12 ## Related in other subjects - [Typical water supply system and components](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Atypical-ws-system-components) — Water Supply Engineering, chapter 1, asked 4× - [Water supply system and historical development](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aws-historical-development) — Water Supply Engineering, chapter 1 - [Protection and maintenance of water supply](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aws-maintenance-types) — Water Supply Engineering, chapter 7, asked 4× - [Objectives of water supply and components](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aobjectives-ws-rural-diagram) — Water Supply Engineering, chapter 1, asked 3×