Water-demand variations – typical design value for maximum hourly consumption In municipal water-supply design, the 'maximum hourly' consumption is commonly taken as what percentage of the average hourly consumption?

Introduction / Context:
Demand factors account for peaking behavior within a day or year. Designers adopt empirical multipliers to size transmission mains, service reservoirs, and pumps to cope with short-duration peak loads.

Given Data / Assumptions:

• Typical urban distribution without extreme industrial fluctuations.
• Average daily demand known; average hourly is daily average divided by 24.
• Standard peaking factors used in preliminary design.

Concept / Approach:
A common rule-of-thumb is that maximum hourly consumption is about 1.5 times the average hourly consumption (150%). This recognizes diurnal peaks in morning/evening. More refined designs further consider 'maximum day' factors and 'peak hour on peak day' factors, but for many exam and planning contexts, 150% is the accepted figure.

Step-by-Step Solution:
Let q_avg,h be average hourly consumption.Assume peak-hour factor = 1.5 → q_max,h ≈ 1.5 * q_avg,h.Convert to percent: 150%.

Verification / Alternative check:
Empirical peaking factors in numerous manuals give similar magnitudes; when combined with storage, systems can satisfy peaks without oversizing all conveyance.

Why Other Options Are Wrong:

• 110–140% underestimate peak demands in many communities.

Common Pitfalls:
Using a single factor universally; always refine with local consumption patterns, metering data, and seasonal variations.

Final Answer:
150%