The ambient groundwater quality was compared to the Class 1 recommended value (DWAF, 1996). The lowest or more conservative value of the two is selected.  In instances where the ambient value is selected, it is increased by 10 per cent.  In instances where the ambient quality, of geological origin exceeds the recommended value, the ambient water quality is used.  These poor water quality areas will become exclusion zones in determining the Basic Human Needs Reserve Requirement.  The groundwater quality must comply with the target water quality ranges as shown in Table 8.1.  Table 8.2 shows a summary of the results for the quality aspects at quaternary level in terms of the BHN. Table 8.3 illustrates the groundwater quality class and parameters of concern for each quaternary catchment. Parameters of concern in this case refer to those with elevated concentrations when compared to the drinking water quality standards.