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(h) Some of the waters, especially those arising in the Malmesbury and Cretaceous
beds, approximate sea water in terms of given ionic concentrations.
Group B: Slightly saline chloride waters
(a) TDS values are in the range 300 - 350 mg 1"1.
(b) With the further exception of a lower SO4 content, there is little difference in
percentage composition between the waters of Group A and Group B.
(c) Waters of the Table Mountain Series in Natal and in the Cape ProVince, and waters
arising in the Witteberg quartzites in the Cape have been placed in Group E,
although in terms of percentage composition these waters approximate to Group
B in view of the high chloride content (>31 %).
Group C: Temporary hard (carbonatel waters
(a) TDS values are generally in the range 250 - 400 mg 1" 1 .
(b) The SiO z content is moderately low ranging from 6,5 - 11,0%.
(c) Low concentrations of chlorides in the range 5 - 8% are evident.
(d) The pH is consistently high with an approximate mean of 7,8.
(el A relatively very high temporary hardness is the main .characteristic of Group C
waters. Approximately 68 - 90% of the TDS consists of Ca(HC0 3 )z and
Mg(HC0 3 )z' There is very little permanent hardness.
(f) Waters arising in the basic and ultra basic rocks of the Bushveld Igneous Complex
(especially in the pyroxenic and ultra basic rocks' could be allocated to a sub-group,
given that these waters consist very largely of Mg(HC0 3 '2 with an appreciable
silica content. Ca(HC0 3'z is present in very small amounts.