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.