TOU: Dynamic pricing model and traceability for blockchain-based water supply chain

Efficient pricing mechanisms are critical for optimizing water consumption, managing demand, and promoting equitable resource distribution. This paper presents a Time-of-Use (TOU) dynamic pricing model integrated with Blockchain Technology (BT) to address these challenges. The proposed model categorizes time into Peak, Off-Peak, and Shoulder hours, applying distinct pricing tiers responsive to demand fluctuations, further refined through seasonal adjustments and demand constraints to support sustainability and regulatory compliance. Implemented on the Polygon blockchain - chosen for its low transaction cost, high scalability, and ethereum compatibility - the framework leverages Smart Contracts (SC) for secure, transparent and automated real-time pricing adjustments. Full on-chain data storage eliminates off-chain dependencies, ensuring data integrity and traceability throughout the water supply chain. Pseudonymous blockchain identities maintain user privacy while providing full auditability via immutable on-chain records. Security vulnerabilities such as input manipulation, arithmetic overflows, and unauthorized access receive proactive mitigation through secure coding practices, role-based access control, and logic constraints. Performance evaluation using the k6 load testing tool under simulated real-world conditions shows robust system behavior: response times ranged from 2.14s to 5.64s, with the 90th and 95th percentiles at 3.5s and 4.26s, respectively. Latency ranged from 5.96ms (median) to 49.54ms (95th percentile), validating the system’s responsiveness, scalability, and reliability under concurrent user requests. The test results further highlight the system’s ability to handle concurrent user requests efficiently, demonstrating reliable performance under simulated varying workloads.