Feasibility Analysis of Decentralized Pressure Improvement in Peripheral Water Networks: Case Study of Zone 3, Surabaya, Indonesia

The study evaluates shifting Surabaya’s low-pressure coastal area (Zone 3) from a centralized to a decentralized water treatment system. Current residual pressure is below 2 mH2O, failing the 5–10 mH2O standard, and Scenario 1 shows the existing system cannot meet 2030 demand. Scenario 2, following the utility’s centralized expansion (Karang Pilang IV WTP, Putat Gede 3 Booster Pump, Mbah Ratu Reservoir), reaches 88% of customers at adequate pressure by 2030 but requires IDR 219.98 billion. A decentralized alternative with a local 500 L/s WTP and 900 m3 reservoir dedicated to Zone 3 achieves 98% coverage at the required pressure for only IDR 100.5 billion. The study concludes that decentralized systems can more effectively and cost‑efficiently boost pressure and meet growing demand where raw water sources are limited and centralized expansion is insufficient.