The hardness of water reflects the nature of the geological formation with which it has been in contact. The major portion of total hardness is caused by calcium and magnesium ions and plays role in heart disease in human. The TH of the groundwater was calculated using the formula as given below (Sawyer and McCartly 1967). (1)
Table 3: Groundwater classification based on total hardness (Sawyer and Mc Cartly 1967)
Total Hardness as CaCO3 (mg/l) Classification Percentage of samples
< 75 Soft -
75 - 150 Moderately high -
150 - 300 Hard 06.45
> 300 Very hard 93.55
For total hardness the most desirable limit is 80-100 mg/l (Freeze and Cherry 1979). Groundwater exceeding the limit of 300 mg/l is considered to be very hard (Sawyer and McCartly 1967). In the study area 6.45 % and 93.55% (Table 3) of the samples fall in the water type of hard and very hard type respectively. TH ranges from 212 to 3,600 mg/l with the average value of 777 mg/l. The spatial distribution of the TH is shown in Fig. 6. 74.19% of the study area surpasses the maximum allowable limit of 500 mg/l. This is due to the discharge of untreated effluents from the textile dyeing units. Fig. 6 Spatial distribution of total
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It is observed that mean values of all the concentrations of cations viz., Ca2+, Mg2+, Na+ and K+ ions are exceeded the desirable standard limit. The order of abundance is Ca2+ > Mg2+ > Na+ > K+. Sewage and industrial wastes are the important sources of calcium and magnesium (Subrahmanyam and Yahadaiah 2001). The spatial distribution of dominated cation Ca2+ and Mg2+ are presented in Fig. 7 and Fig. 8 respectively. Bicarbonate represents the major form of alkaline, since it is formed in considerable amounts from the action of carbon dioxide upon basic materials in the soil (Sawyer et al