Nitrate concentrations in Riyadh, Saudi Arabia drinking water supplies

Riyadh, Saudi Arabia is supplied with drinking water from both desalinated sea water and treated groundwater sources. Samples were analysed for NO3 from selected deep and shallow wells, two locations within the city's six groundwater treatment plants, the desalinated sea water and distribution network. Average nitrate concentrations (as NO3) were 8.2 and 15.8 mg/L for deep and shallow well waters, respectively. The average nitrate concentrations (as NO3) in the groundwater treatment plants influent waters and the final product water were 16.2 and 8.5 mg/L, respectively. Due to blending of the plants' product water with the desalinated sea water, the average network nitrate concentration was 4.4 mg/L. The scheduled water interruption does not seem to cause any appreciable change in the nitrate levels in the distribution network.