Geochemical Characterization and Management Challenges of Groundwater in Dhaka City, Bangladesh.

Abstract

Effective groundwater management is critical for ensuring public health and sustainable water use, particularly in rapidly urbanizing regions such as Dhaka City, Bangladesh. This study assesses groundwater quality and its implications for human health through geochemical analysis of thirty-five (n = 35) deep and shallow tube well samples across an area of approximately 306 sq. km. Key physicochemical parameters indicate that the water ranges from slightly acidic to near neutral (average pH 6.91), with low turbidity (avg. 1.31 NTU), and a redox environment varying from reducing to oxidizing (ORP –77.4 to 153 mV).
Elemental analysis conducted using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) reveals that most parameters, including chloride (20.46 mg/L) and zinc (0.11 mg/L) fall within permissible limits. However, iron (0.38 mg/L), cadmium (0.002 mg/L), lead (0.004 mg/L) and fluoride (7.86 mg/L) concentrations exceed World Health Organization (WHO) thresholds in several locations, signaling localized contamination risks. Fluoride distribution mapping shows a spatial imbalance, with two-thirds of the study area exhibiting excess fluoride and one-fourth showing deficiency; both of which may cause dental and skeletal health issues.
The Water Quality Index (WQI) classifies 40% of the samples as “excellent” and 60% as “good” for drinking purposes. Despite this, challenges such as over-extraction of aquifers, unplanned urban growth, and increasing industrialization continue to threaten groundwater sustainability and quality. The study emphasizes the urgent need for an integrated groundwater management framework that incorporates pollution control measures, equitable water distribution, periodic quality monitoring, and public health awareness campaigns. These actions are essential to preserving groundwater resources and ensuring long-term water security for the growing urban population.