The pH value is a dimensionless measure of the acid, neutral or basic character of an aqueous solution. The activity of the hydrogen ions is measured and then calculated. The pH scale is a logarithmic scale from 0 to 14 without any dimension. A pH value of 7 being considered neutral. This is also the pH of distilled pure water without solved CO2 in it. Values smaller than pH 7 are considered acidic and values bigger than 7 pH are considered alkaline.
Hence at the lower end of the scale one will find the acids whereas at the higher end of the scale the bases.
The pH value of drinking water
The authorities stipulate that drinking water should have a pH of not less than 6.5 and not more than 9.5. Therefore a lot of waterworks are adding lime slurry to the raw water. To bring down the pH, to come as close as possible to a neutral pH of 7.
To make this rather dry pH value, a little bit more understanding here a few examples. The pH value of:
|pure water 7.0
|sulfuric acid 2.75
|acid rain 5.0
|human urine 6.0
|caustic soda 14.0
This pH values in the table above are average values, they might vary from case to case. The pH of the human urine for instance, depends a lot on the diet, the medicines or the diseases one has. It can go as low as 5.0 considered as acidic or as high as 8.5 considered alkaline.