Journal of Information System Exploration and Research
Vol. 4 No. 4: October 2026

Unsupervised Anomaly Detection for Water Pump Fault Identification Under Extreme Class Imbalance

Mochamad Rizal Fauzan (Department of Electrical Engineering, National Taipei University of Technology, Taiwan)
Ghayrie Habsy Alghifary (Faculty of Engineering Education and Industry, Universitas Pendidikan Indonesia, Indonesia)
Muhamad Husen (Faculty of Engineering Education and Industry, Universitas Pendidikan Indonesia, Indonesia)



Article Info

Publish Date
08 Oct 2026

Abstract

Water pump fault detection in industrial systems is challenged by extreme class imbalance, where anomalous states account for less than 7% of operational data and labeled fault examples are scarce. This paper presents a comparative evaluation of three unsupervised anomaly detection approaches Isolation Forest (IF), Long Short-Term Memory Autoencoder (LSTM-AE), and One-Dimensional Convolutional Neural Network Autoencoder (1D-CNN-AE) applied to a real-world multivariate water pump sensor dataset comprising 220,320 one-minute observations across 51 sensors. All models are trained exclusively on normal operational data, eliminating dependence on fault labels. A sliding-window preprocessing pipeline (W = 30 timesteps) with a scaler fitted only on normal training data ensures no temporal data leakage. Anomaly thresholds are derived statistically (mean + 3σ) from reconstruction errors on the normal test partition. Using a chronological 60/40 train-test split and threshold-free metrics, Isolation Forest achieves AUROC = 0.9973 and Recall = 0.9850, while LSTM-AE yields F1 = 0.9218 and Precision = 0.8892. The results reveal a fundamental sensitivity-selectivity trade-off across unsupervised paradigms and provide actionable guidance for deploying anomaly detection in water infrastructure monitoring systems.

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Journal of Information System Exploration and Research is a journal that publishes and disseminates scientific research papers on information systems to a wide audience particularly within the information system ...