Heavy metals, defined as those metallic elements with a specific gravity at least five times that of water, are common in nature and human exposure may come from drinking water or food. Most of the heavy metals are either rare enough to be found in water or are essential in providing nutrition to the human body. However, several of them are toxic and should be regulated and monitored.
According to the World Health Organization (WHO) Guidelines for drinking-water quality, the concentration of the heavy metals in drinking water should be smaller than the guideline values.
Guideline values (mg/L)
Besides testing heavy metals, there are groups of chemicals that arise from related sources – for example, disinfection by- products (DBPs). If chlorination is practiced, the trihalomethanes (THMs) and haloacetic acid (HAAs) will be the main DBPs.