Post-earthquake monitoring of drinking-water quality and health risk in Kahramanmaraş Province, Türkiye: a two-timepoint screening assessment.

The February 2023 Kahramanmaraş earthquakes damaged water-supply infrastructure, but post-earthquake drinking-water quality and health risk in the epicentral region remain poorly characterized. This study assessed trace element contamination and cumulative human health risk in municipal drinking water from all 11 districts of Kahramanmaraş Province at ~ 18 (August 2024) and ~ 24 months (February 2025) post-earthquake, using ICP-MS, the Water Quality Index, deterministic/probabilistic (Monte Carlo) health risk assessment, and multivariate statistics. All concentrations remained below drinking-water guideline values (WQI = 3.1-13.4), yet substantial spatial heterogeneity was observed. Children were most vulnerable, with hazard index > 1 in up to four districts per campaign; arsenic contributed ~ 76% of cumulative non-carcinogenic risk. Deterministic carcinogenic risk exceeded the 1 × 10-4 benchmark in 21 of 44 district-period-population combinations, consistently in Afşin, Türkoğlu, and Elbistan; these exceedances reflect the substantially higher arsenic cancer slope factor adopted in the January 2025 US EPA IRIS update (32 (mg/kg/day)-1, versus 1.5 previously) rather than a deterioration in measured arsenic concentrations, all of which remained below the WHO/TS266 guideline value. Monte Carlo simulations identified the same districts as recurring, screening-level exceedance hotspots. These findings are consistent with the hypothesis that major earthquakes can shape drinking-water exposure patterns long after the immediate disaster period, although the absence of a pre-earthquake baseline or control area precludes direct causal attribution. This study provides the first province-wide assessment of post-earthquake drinking-water quality and health risk following the 2023 Türkiye earthquakes, underscoring the need for cumulative, probabilistic, and long-term monitoring in post-disaster water management.