Assessment of physico-chemical properties, bacterial contamination, and water quality interrelationships in lanyiru spring, meru county, kenya

Abstract

Reliable access to clean water is critical for public health, economic growth, and environmental sustainability. However, rural communities in Kenya continue to face water quality challenges stemming from contamination, inadequate monitoring, and fluoride pollution. Springs like Lanyiru in Meru County are commonly assumed safe based on appearance, yet the absence of regular assessments poses unrecognized health risks. This study assessed the physicochemical and microbial quality of Lanyiru Spring water to determine its suitability for domestic use. Samples were collected from four sites along Lanyiru Springs at the middle of wet and dry season (September 2025) and were analyzed through both in situ measurements and laboratory procedures. Physical parameters including pH, temperature, turbidity, conductivity, and total dissolved solids were measured on-site with calibrated instruments to ensure accuracy. Chemical analyses, encompassing cation and anion quantification, were conducted in the laboratory following APHA and EPA standard methods, employing techniques such as Flame Atomic Absorption Spectrometry (FAAS), Inductively Coupled Plasma–Mass Spectrometry (ICP-MS), ion chromatography, and ion-selective electrodes. Microbial contamination was assessed via the Most Probable Number (MPN) method for coliform bacteria. Data collected were analyzed using R software (version 4.3.0), with significance determined at α = 0.05, to detect spatial variations and assess water quality relative to health standards. Significant spatial variations (p < 0.05) were observed in key cations, including Pb2+, Fe2+, Cd2+, Cu2+, Ca2+, Mg2+, and K+. Notably, Pb2+ peaked in Sample LP1A and LP1B (0.008 mg/L), Fe2+ at LP4B (10.03 mg/L), and Cd2+ at LP3A (0.041 mg/L), exceeding recommended limits and indicating contamination risks. Cu2+ was highest at LP4B (0.342 mg/L), with elevated Ca2+ and K+ also recorded at LP4A. Anion analysis revealed significant differences in SO4², Cl, and F concentrations across sites. Sample LP4A exhibited the highest SO4² (132.85 mg/L) and Cl (311.90 mg/L), while LP4B showed the highest fluoride level (8.40 mg/L), exceeding WHO guidelines. The Na+ levels showed no significant spatial variation (p > 0.05). Physical parameters showed no significant variation in pH (mean = 10.16), indicating overall alkalinity, but temperature varied significantly, with LP2 recording the highest at 26.87°C. Lanyiru Spring water is contaminated with heavy metals, elevated fluoride, turbidity, and microbial hazards from both natural and human activities, making it unsafe for direct consumption. To protect community health, regular water quality monitoring, pollution control, improved sanitation, household water treatment, and investment in alternative safe water sources are urgently needed.