Drinking water quality, heavy metals, sulphate, Aluminium,
This is a joint work between the Italian Red Cross and the Environmental Laboratories, Baghdad. The drinking water (DW) samples from 16 residential districts in Baghdad were chemically evaluated with reference to the raw water samples and water directly taken from the purification plants. In addition to the routinely measured parameters, 17 metals and 11 trihalomathane (THM) were measured. Generally, the samples of water analysed can be considered of good quality. The relatively high sulphate and aluminium contents results from the use of aluminium sulphate as flocculent. The ammonia and Nitrite concentrations were lower than the detectable limit, because ammonia is converted into chloramines and nitrite is converted into Nitrate during chlorination. This indicates no sewage contamination of the drinking water. The high chloride contents can be referred to the use of partially degraded hypo for the disinfection. The presence of THM's in the samples analysed is indicative of good disinfection process. The presence of these compounds is preferred better than bacterial contamination. The relatively high levels of zinc and iron have no impact on the quality of DW. Iron, however, was efficiently removed during the treatment, together with Manganese. Reference was done to the EU specification of drinking water regarding total hardness, chloride contents, sulphate, iron and THM's. As for the iron content, the original pH of the river water (7.5 and 8.0) ensures that Iron should not be present in soluble form at a detectable level. Corrosion of the pipes could be one of the reasons for the presence of iron.
Key Words: Drinking water quality, heavy metals, sulphate, Aluminium, Trihalomethans, hardness.