Proportion of domestic use in total city water demand: For planning purposes, what fraction of the total municipal water supplied is typically assumed to be domestic consumption?

Introduction / Context:
Municipal demand is divided into domestic, industrial/commercial, public uses (parks, schools, street washing), firefighting provision, and losses (leakage and unaccounted-for water). Concept-level planning often applies empirical percentage splits when local metered data are unavailable. This question checks a commonly adopted share for domestic use.

Given Data / Assumptions:

• Medium-sized Indian city without dominant heavy industry.
• Conventional planning values from textbook practice.
• Domestic fraction is intended as a representative planning number.

Concept / Approach:
Many syllabi and standard references treat domestic consumption as the single largest component but not the entirety of demand. Typical ranges are 35–55%, with 40% being a widely used assumption in preliminary estimates when detailed sectoral data are absent.

Step-by-Step Solution:
List typical components: domestic, industrial/commercial, public uses, firefighting, losses.Adopt the representative split: domestic ≈ 40% of total supply.Select the option that matches the standard assumption.

Verification / Alternative check:
Where utilities have metered data, domestic often falls near 40–50%. The 40% value is conservative when industry is moderate and system losses are significant (common in older systems).

Why Other Options Are Wrong:

• 20% and 30%: usually too low for most Indian municipal systems.
• 60% and higher: may occur in dormitory towns with low non-domestic use, but are not typical planning defaults.

Common Pitfalls:

• Treating these splits as universal; actual shares should be refined with local data.
• Confusing domestic consumption with per-capita allocation, which is a separate parameter (e.g., LPCD).

Final Answer:
40%