pH of drinking water : pH of drinking water : document for public consultation

Definition and measurement 4.1 Definition of pH At a given temperature, the intensity of the acidic or basic property of the water is indicated by the pH, which is the negative logarithm of the hydrogen ion activity (APHA et al., 2012). [...] Based upon the Nernst equation, the term “2.303 RT/nF” is called a “slope factor” and describes the change in the total potential between the measuring and the reference electrodes for + every 10-fold change in the activity of the H. ion. [...] The respiration of algae or the biodegradation of organic matter increases the carbon dioxide concentration and decreases the pH of the water. [...] Whereas alkalinity is a measure of the capacity of the water to neutralize acids, buffer intensity is an ability of the water to provide resistance against the pH fluctuations caused by the addition of water treatment chemicals or by water quality changes in the distribution system. [...] This ability of the water to resist pH fluctuations is strongly influenced by the DIC concentration, pH and alkalinity of the water and is also a function of temperature and ionic strength.