Statistical analysis of water quality in the drinking water treatment plant of the municipality of Tarqui (Huila, Colombia)

Abstract

The supply of drinking water is essential for the development of human activities. The objective of this research was to statistically evaluate the quality of the water in the drinking water treatment plant of the municipality of Tarqui (Huila, Colombia). Monthly data was collected for six years, corresponding to 2010, 2011, 2012, 2013, 2014, and 2016. The study considers four phases: descriptive application, exceedance in the quality of treated water compared to international and national regulations, risk index estimation for the quality of drinking water WQRI, water quality index WQI, and the evaluation of contaminant removal for treated and untreated water. For the treated water parameters, turbidity (r = 0.58), pH (r =0.69), and free residual chlorine (r = 0.55) were the best control parameters. The average turbidity values (2.35 UNT) were significantly higher in 2010 and 2011 and presented a minimum value (0.93 UNT) in the remaining years. Maximum and minimum values for pH were 7.74 and 6.81 in April 2013 and February 2014, respectively. The best correlation occurs between BOD5 and COD parameters (r = 0.99), with mean values of 7.23 mg/L and 18.40 mg/L, respectively. 33% of the years analyzed presented a WQRI parameter consistent with low-risk conditions in the study period. The remaining 67% of the years presented a WQRI value associated with no risk for human consumption. The ICA parameter shows that the raw water of El Hígado creek is suitable for human contact. It is concluded that the water treated in the purification plant of the municipality of Tarqui is suitable for human consumption and does not represent threats to the health of its consumers.