• • The rod-shaped bismuth-based electrode achieved a detection limit of 0.34 μg·L−1 for Pb(II), which is below the WHO guideline of 10 μg·L−1 for drinking water, enabling trace-level monitoring.
• • Sensitivity was measured at 106 μA·(μmol·L−1)−1, indicating high electrochemical activity and strong signal response, facilitating accurate quantification in low-concentration ranges.
• • The linear detection range spans 1–90 μg·L−1, covering typical contamination levels in environmental waters, thus suitable for routine screening.
• • The sensor demonstrated high recovery rates in real water samples (tap water and campus lake water), confirming its reliability and potential for on-site monitoring in public swimming pools.