Water quality has a major importance for public health. However, nitrite and nitrate levels in water are still an im-portant contamination issue in the world. The aim of this study was to determine the levels of total nitrite and nit-rate in public water (tap water) and wells from different districts of Istanbul city and to evaluate the seasonal varia-tion from November 2013 to March 2014. The average levels in tap waters were highest in March 2014 compared with November, December 2013 and February 2014. Two of the tap water and 3 of the well water samples exceed the maximum acceptable concentration according to the U.S. Environmental Protection Agency (10 ppm). However, these levels were still lower than the maximum allowable limits reported in official documents of Tur-key. Also, in order to determine the annual variation, tap water samples were collected between December 2012 and February 2013 and evaluated for total nitrite and nitrate levels. Results showed that total nitrite and nitrate levels during December 2013 and February 2014 were decreased in the ratio of 2, 10 and 18% compared to the sa-me months during December 2012 and February 2013. In conclusion, our results suggested that due to seasonal and annual variations, nitrite and nitrate levels of waters should be routinely controlled to prevent various health hazards.
Keywords: Nitrite, Nitrate, Tap water, Safety