How much water should a person receive each day? In India, this question is not answered by science or necessity, but by an arbitrary metric — the per capita water supply standard, prescribed in litres per capita per day (lpcd). While the human right to water guarantees access to safe and clean water, and obligates governments to provide basic services, in practice this right is shaped by the per capita standard. This benchmark not only dictates how much water citizens are entitled to demand for their daily needs, but also drives planning and investments in urban water infrastructure, from dams to household taps. Yet, despite its widespread use by municipal authorities across India, it lacks empirical grounding, objective rationale, and validity, making it a policy instrument built more on convenience than evidence.