HYDROGEOCHEMICAL FACIES AND DRINKING-WATER SUITABILITY OF GROUNDWATER IN OIL-IMPACTED NIGER DELTA COMMUNITIES: A PIPER DIAGRAM AND WHO COMPLIANCE ASSESSMENT OF OKERENKOKO, KURUTIE, AND KUNUKUNUMA, DELTA STATE, NIGERIA

Abstract

The assumption that petroleum contamination is the primary source of hydrochemical character 
in coastal Niger Delta aquifers is widely accepted but can be tested directly through facies-level 
analysis. This study characterised the hydrogeochemistry of groundwater from three communities 
(Okerenkoko, Kurutie and Kunukunuma) in the Gbaramatu Kingdom of Warri South-West, Delta 
State, using 30 sampling points and Piper trilinear diagram classification. Groundwater was 
consistently acidic (pH 4.34–5.76, mean 4.96 ± 0.73), with total dissolved solids (80.6–212.75 
mg/L) and salinity (92.8–109.9 mg/L) within WHO (2022) limits, but chloride (319.78–360.2 
mg/L) and fluoride (2.47–2.98 mg/L) exceeded permissible thresholds. Piper classification 
identified a near-uniform Mg²⁺–Cl⁻ hydrochemical facies across all sites, attributed to marine 
influence rather than to petroleum contamination. A simple mixing estimate using Cl⁻ suggests 
approximately 2% seawater mixing in the shallow aquifer. A combination of high chloride and low 
alkalinity suggests corrosive water quality and irrigation suitability is rated C3–S2 to C4–S3 (salt
tolerant crops only). The study establishes a baseline for the hydrogeochemistry that supports the  fact that groundwater throughout the region is impacted by regional controls and not local 
controls, therefore necessitating regionally coordinated water-treatment intervention.