The Applicability of the Local and International Water Quality Guidelines to Al-Gassim Region of Central Saudi Arabia

Abstract

The quality of 109 water samples, comprised of 70 drinking waterand 39 irrigation water samples, in Al-Gassim Region of SaudiArabia was investigated with respect to total dissolved salts(TDS), electric conductivity (EC), pH, total hardness and themajor cations (Ca2+, Mg2+, Na+ and K+) andanions (Cl-, SO42-, NO3-,F- andHCO3-) beside coliform bacteria as an indicator offaecal contamination.The concentrations of TDS varied widely, from 109 to 6995 mgL-1, with a mean of 1427 mg L-1. Of the 109 watersamples examined, 81 (74.3%) comply with the maximumpermissible drinking water limits set by the local and international standards and guidelines and 28 (25.7%) were abovethe limits of these standards. The concentrations of the cationsand anions (with the exception of NO3- and F-)follow, more or less, a trend similar to TDS. NO3- concentrations (range 0–30 mg L-1) comply with the limitof 50 mg L-1 NO3- as the highest tolerableNO3- content. The concentrations of F- indrinking water (range 0.2–1.5 mg L-1) are alarming since88% of samples were below the lower permissible limit of 0.6 mgL-1 set by SASO (1984), the guideline of the WHO is 1.5 mgL-1 while the EEC maximum concentration lies within the range 0.7–1.5 mg L-1. Microbiological analyses showednegative coliform tests, which confirms that they are devoid ofany faecal contamination.