Water is a vital resource for the universe's survival of both flora and fauna, broadly referred to as an elixir of life. However, high population growth, encroachment of catchment areas, and climate change have rendered water resources scarce, leading to reliance on alternative groundwater sources to supplement the less freshwater sources for domestic, agricultural, and industrial use. Groundwater is considered a reliable source of uncontaminated water for various uses in rural and urban settings, especially for drinking. However, the uncertain potability of groundwater sources such as springs and boreholes remains a great concern, particularly when used untreated for human consumption, posing serious human health threats. This study assessed the physico-chemical quality using selected groundwater parameters from a natural spring (Mwonyo) at Nkubu, Nkuene ward, Meru County, Kenya, to determine its suitability for human consumption. A systematic sampling design was employed and a total of four water samples were collected in triplets of 500 ml water bottles and analyzed in the laboratory following standard analytical procedures using specific meters and Atomic Absorption Spectrophotometer (AAS). Examined parameters included; color, taste, electrical conductivity, dissolved oxygen, pH, temperature, and turbidity, as well as concentrations of phosphate, fluoride, ammonia, nitrite, and nitrate ions. The results were compared with the maximum contamination levels (MCLs) by the Kenya Bureau of Standards (KEBs) and World Health Organization (WHO) guidelines for drinking water quality to determine the suitability of the sampled water for drinking purposes. The study findings showed that the sampled water exceeded permissible limits for several physico-chemical parameters, including low pH (6.36), high electrical conductivity (2380 μS/cm), turbidity (16.30 NTU), and elevated concentrations of phosphate (0.12 mg/L), ammonia (0.86 mg/L), and fluoride (122.8 mg/L), indicating potential contamination originating from natural and anthropogenic sources. The study recommends further investigation and appropriate water treatment interventions to ensure public safety. While some other parameters were within the permissible levels e.g., temperature (28.3°C), dissolved oxygen (4.2 mg/L), and nitrates (0.57 mg/L), the overall water quality was deemed unsuitable for drinking without undergoing treatment. These parameters might be influenced by the geological makeup of the region and seasonality. This study thus recommends further investigation and appropriate water treatment interventions to ensure human health safety.