Hidrología: investigaciones actuales

Chemical Test Measurements for Potable Water Quality: A Preliminary Test Correlation Study in the Umgeni Water Catchments, Kwazulu-Natal, South Africa

Abstract

Manickum T

In the potable water sector, many decisions are based on the actual test measurement results. It is thus critical that such test results are consistently accurate, valid and reliable. From the various drinking water quality tests data, four chemical tests results and ratios, collected over a 2-year period, were evaluated for any significant correlation: Alkalinity (total) vs. Hardness, Total dissolved solids (TDS) vs. Conductivity (EC), Conductivity vs. Sodium [Na+], and Conductivity vs. Chloride [Cl-]. Of the 9 water works investigated in this preliminary study, 3 sites showed a significant correlation for all 4 comparisons, two other sites had 3 significant water quality relationships, one other site had 2 significant water quality relationships, and two other sites had 1 significant water quality relationships. The average (range) ratios were: Alkalinity/Hardness = 0.9 (0.7-1.1), TDS/EC = 6.3 (5.5-8.5), EC/ [Na+] = 1.1 (0.7-2.0) and EC/ [Cl-] = 0.8 (0.5-1.3). The derived regression equations were used to calculate the water quality parameters (Hardness using Alkalinity, Conductivity using: TDS, [Na] and [Cl-]), which were evaluated for accuracy; the percentage error was generally within ± 10% for 91% of the calculated water quality test parameters. The observed trends (ratios), per site, can be used as an additional accuracy check for the individual, analytically measured, regulatory drinking water quality tests data to facilitate decision making.