--- title: "Criteria for selecting a water source" subject: "Water Supply Engineering" chapter: 2 key: "semester_5/water_supply_engineering:selection-criteria-water-source" source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/selection-criteria-water-source site: BCT Engineering --- # Criteria for selecting a water source Water Supply Engineering · Chapter 2: Sources of Water - Asked in: 2078 Bhadra, 4 marks; 2079 Bhadra, 4 marks; 2072 Kartik, 4 marks; 2070 Asar, 4 marks; 2074 Asoj, 4 marks (asked 5 times) - Video: [Unit:2 | Criteria for the Selection of Source of Water | Diffe betn Ground Source & Surface Source |](https://www.youtube.com/watch?v=W-9Mrb5yeRw) — Prashant YT - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/selection-criteria-water-source - Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-2 ## Question Describe the selection criteria to choose a source of water supply. ## Short answer Select a source with adequate dry-season yield, good or easily treatable quality, high elevation for gravity supply, low capital and O&M cost, reliability, legal water rights, accessibility, minimal environmental impact, and future expansion potential. Preference is usually protected spring or gravity source, then ground water, then surface water requiring treatment and pumping. ## Answer The source should be chosen so that the scheme gives the best water at the least cost and with long-term reliability. The main criteria are: 1. **Quantity:** The yield of the source in the driest season must meet the demand at the end of the design period, preferably with a margin. Springs and streams should be gauged in the dry season. 2. **Quality:** The water should be wholesome or easily treated. Sources free from pollution risk, such as springs in forested catchments, are preferred. Ground water is usually free from turbidity and bacteria. 3. **Elevation and location:** A source at a higher level than the town allows a gravity scheme, avoiding pumping costs. The distance from the consumers should be short. 4. **Cost:** Capital cost (intake, pipe, treatment, pumping) and operation and maintenance cost should be low. Compare alternatives on a life-cycle basis. 5. **Reliability and sustainability:** The source should not dry up or get polluted in future and should not be threatened by landslides or floods. The catchment should be protected. 6. **Ownership and water rights:** Legal rights of existing users, irrigation and mills should be respected; no social conflict. Permission is needed under the Water Resources Act. 7. **Accessibility and safety:** Site should be reachable for construction and maintenance and have good, stable foundation. 8. **Environmental effect:** Minimum effect on downstream users, ecology and land. 9. **Future expansion:** The source should permit increase in supply later. Where several sources exist, the order of preference is usually: protected spring or gravity source, ground water, then surface water that requires treatment and pumping. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. The yield of a source should be checked in: A. The wettest season B. The driest season against demand at end of design period C. Any season D. Winter only Answer: B. Dry-season yield must meet end-of-design-period demand. (Key point: Quantity criterion) 2. Why prefer a source at higher level than the town? A. Gravity flow avoids pumping cost B. Better taste C. Less rainfall D. Lower turbidity Answer: A. A higher source allows gravity supply and avoids pumping cost. (Key point: Elevation) 3. The usual order of preference is: A. Surface water, ground water, spring B. Ground water, spring, surface water C. Protected spring or gravity source, ground water, then surface water with treatment and pumping D. River, lake, spring Answer: C. Gravity springs come first, then ground water, then treated and pumped surface water. (Key point: Order of preference) 4. Why consider ownership and water rights? A. To raise tariff B. To avoid conflict with existing users and meet legal permission C. To reduce quantity D. To increase hardness Answer: B. Rights of irrigation, mills and others must be respected and permission obtained. (Key point: Water rights) ## Related in Water Supply Engineering - [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× - [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× - [Necessity and impacts of water supply scheme](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Anecessity-impacts-ws) — Water Supply Engineering, chapter 1, asked 3× - [Objectives of supply; wholesome water requirements](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aobjectives-requirements-wholesome) — Water Supply Engineering, chapter 1, asked 2× - [Importance and objectives of water supply](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aimportance-objectives-ws) — Water Supply Engineering, chapter 1 ## Related in other subjects - [Criteria for selecting a processor](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Aprocessor-selection-criteria) — Embedded System, chapter 2, asked 2× - [Criteria for selecting a suitable scale](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Acriteria-selecting-scale) — Surveying I, chapter 1, asked 2× - [Selection criteria for ADC](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aadc-selection-criteria) — Instrumentation II, chapter 4, asked 3× - [Selection criteria of hydraulic turbines](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Aturbine-selection-criteria) — Hydro Power, chapter 7, asked 2×