Development and standardization of taste-rating of the water sample as a semi-quantitative assessment of iron content in groundwater

Abstract

The present study attempted to develop and standardize a simple tool of taste-rating of groundwater sample for the level of iron as a semi-quantitative assessment of iron content in groundwater. An observational study was conducted involving randomly selected 666 households with the drinking source of groundwater (e.g. tube-wells) in a high-iron and in a low-iron groundwater area of rural Bangladesh. The respondents of the households were asked to provide their taste-rating of the respective tube-well water. Two external assessors also taste-rated the water samples. Taste-ratings were standardized as “no-iron”, “some iron” and “heavy iron”, based on perceived taste sensation of the water sample experienced, such as “sweet”, “bitter”, “burning”, “sticking” etc. The iron concentration of the well-water was measured using a portable colorimetric test-kit device to compare and standardize the test ratings. In the high-groundwater-iron area (n = 400), the mean iron concentrations were 3.69 mg/L, 3.93 mg/L and 7.71 mg/L in the “no”, “some” and “heavy” categories respectively (p = 0.001). In the low-groundwater-iron area (n = 266), the respective concentrations of iron in the well-water for the taste-categories were 0.08 mg/L, 0.68 mg/L and 3.26 mg/L (p < 0.001). There was a small agreement between the assessors and the respondents (Kendall's τ b = 0.14, p = 0.004; Lin's concordance = 0.13, p = 0.004), however the inter-assessor agreement was high (Kendall's τ b = 0.79, p < 0.001; Lin's concordance = 0.77, p < 0.001). Taste-ratings of the water samples have the potential to use as a semi-quantitative tool for measuring iron content in groundwater. External assessors may provide a reliable assessment.