QUALITY OF POTABLE WATER IN THE CITY OF ASCENCION, CHIHUAHUA, MEXICO

The objective of this study was to evaluate water quality by physical-chemical and metal-microbiological analysis. Water samples were obtained from five wells that provide potable water and from five randomly selected households in the city of Ascencion during four seasons. The samples were collected in July 2011 (summer), September 2011 (autumn), December 2011 (winter) and May 2012 (spring). Hence, a total of 40 water samples were analyzed for potential hydrogen (pH), electrical conductivity (EC), temperature (T), dissolved oxygen (DO), turbidity (Turb), total solids (TS), total coliforms (TC), fecal coliforms (FC) and the following metals; Al, As, B, Cd, Ca, Cu, Cr, Fe, Mg, Mn, Ni, Ag, Pb, K, Na, Se, Si and Zn. For the metal data, an ANOVA was performed to look for seasonal differences (Factor A), well/household differences (Factor B) and their interaction using a 0.05 level of significance. About 80% of the water samples tested positive for TC and FC and the lowest number of coliforms was found in the winter samples. These results are very important because it is widely recognized that outbreaks of many waterborne diseases are caused by contaminated groundwater. The pH was changed according to the season (P<0.05), with 8.7 for summer and for autumn, 9.7 for winter and 9.2 for spring. The EC values did not change with the seasons (P>0.05). Temperature was statistically changed (P<0.05) according to the season, with 16° C in winter, and 27° C in autumn. The TS was not different (P>0.05), while DO was (P<0.05), with 15 mg L^-1 noted in autumn samples and 1.45 mg L^-1 in spring samples. The turbitity parameter was not detected in any of the samples. Metal levels varied differently according to each metal.