Average domestic per-capita water demand in Indian cities: Under normal planning and design conditions, which value best represents the typical domestic component per person per day?

Introduction / Context:
Per-capita water demand (LPCD) guides sizing of sources, treatment plants, and distribution networks. Indian planning norms often reference standardized figures for the domestic component, considering bathing, cooking, washing, flushing, and other household uses under typical urban conditions.

Given Data / Assumptions:

• Urban Indian setting with piped supply and sewerage.
• Normal climatic and socioeconomic conditions.
• Average domestic demand, not including significant commercial or industrial loads.

Concept / Approach:
Textbook and guideline values commonly quote 135 LPCD for domestic consumption in Indian cities with sewerage, accommodating indoor plumbing and sanitation. This value serves as a baseline; total municipal supply will exceed this to include non-domestic uses and losses, but the domestic component itself is around 135 LPCD.

Step-by-Step Solution:
Identify parameter: domestic, per-capita, per-day consumption.Recall standard planning figure used in many curricula: 135 litres per capita per day.Choose the option matching this norm.

Verification / Alternative check:
Many DPRs (Detailed Project Reports) and academic problems adopt 135 LPCD as the default domestic figure; sensitivity analyses adjust around this baseline for local context.

Why Other Options Are Wrong:

• 105–125 litres: may reflect constrained supplies or conservation targets; lower than the common planning baseline.
• 150 litres: sometimes used, but 135 LPCD is the widely taught norm for domestic component in Indian urban design contexts.

Common Pitfalls:

• Confusing domestic LPCD with total system LPCD which includes public uses and losses.
• Applying the same figure to rural schemes or water-scarce zones without adjustment.

Final Answer:
135 litres