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Nely Zulfa, S.K.M., M.Si
Journal of Engineering, Infrastructure and Geosciences (2026)
Coverage indicators for water and sanitation are usually reported and read as a pair, assuming the two services face similar constraints and progress at similar rates. This article shows that the assumption fails systematically rather than locally, and explains why. In Central Java Province, Indonesia, a jurisdiction of some 37 million people, basic water supply reached 92.29 per cent in 2024 and basic domestic wastewater services 92.42 per cent, close enough to read as parallel achievement. The safely managed tiers diverge sharply: safely managed water reached 40.86 per cent against a national standard of 15.00, while safely managed wastewater reached 9.72 per cent against a target of 10.97. Safely managed wastewater was the only indicator in the responsible agency's performance set to miss its target that year, and the province operates no regional wastewater treatment system. The divergence is a predictable consequence of where the safety condition binds in each chain: for water at the point of supply, which investment addresses directly; for sanitation at containment, emptying, transport, treatment and disposal simultaneously, so investment at any single point leaves the condition unmet. Basic-tier parity is therefore not evidence of comparable progress.