Chemical contaminats of concern for drinking water:
While pathogens remain the most important contaminants in drinking water, some chemicals occur in drinking water that are also a significant cause of disease when present at elevated concentrations. There is also an increased perception that many chemicals only found in trace quantities, if at all, are a significant cause of disease.
However, only arsenic, fluoride, nitrate in combination with microbial infection/ contamination and possibly selenium have been shown to cause adverse health effects in humans through drinking water. WHO provides guideline values for many contaminants against which safe levels can be judged and provides advice on how to assess the potential risks of concentrations in excess of guideline values.
WHO also proposes the use of water safety plans to provide a risk assessment/risk management approach to ensuring safe drinking water that also includes identifying and assessing risks from chemical contaminants.