A Step-Drawdown Test a Village Can Actually Run: Separating Well Loss from Aquifer Loss with a Fifty-Two-Dollar Kit, and the Error Budget That Decides When It Cannot

A four-step drawdown protocol using a US$52 airline-gauge kit recovers the Jacob coefficients of a stated village well (B = 1.8 m per (L/s), C = 0.9 m per (L/s)^2) and supports a pre-stated pass/fail rule giving a sustainable rate of 1.33 L/s; a stated 1.5 L/s demand fails on efficiency (57%) despite passing on drawdown. A Monte Carlo error budget gives standard deviations of 0.21 on B and 0.22 on C, correlated at -0.90, a sustainable-rate uncertainty of 0.35 L/s, and a C resolution limit of 0.040 m per (L/s)^2 with a carefully read gauge. Two wells with opposite failures, identical at any single pumping rate, differ by 37 standard deviations at the top step. SIMULATED, NOT MEASURED.