Water treatment Water treatment Water taken from boreholes is already clean because it is filtered as it trickles through soil and rocks. Normally it is only necessary to disinfect this water with chlorine to make it safe to drink.
Water taken from rivers and reservoirs usually needs more treatment.
Water Treatment Works treat water so that it is safe to drink. This involves a number of processes, both physical and chemical, and will vary depending on the quality of the raw water to be treated. Flocculation - the water is passed through big tanks where a number of chemicals are added, including coagulants such as aluminium sulphate or iron sulphate. This floats the floc to the surface of the water where it is scraped off by brushes. The clarified water beneath the floc layer passes through to the filters.