Hardness is measured as mg/L of CaCO3 (calcium carbonate), although the hardness may not necessarily be due to CaCO3. This measure is equivalent to alkalinity and is caused by the presence of multivalent ions such as calcium, magnesium, iron or manganese, released from minerals dissolved in water. Water that is considered hard (150-300 mg/l of CaCO3) generally has lower toxicity than water that is soft (0-75 mg/l of CaCO3) and breaks down soap more easily. The downside is that hard water can cause problems for water treatment processes and in industrial use. Although hardness is not attributed to human activities, it can have a significant impact on infrastructure and water quality and is therefore mentioned here.
Hardness can damage pipes and fittings.
Source: DRFN 2009
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Within the Kunene River basin, hardness in water could cause a problem especially in supplies from groundwater sources. Hardness causes scaling in water pumps, and damages valves, pipe fittings and other infrastructure especially in rural systems that draw groundwater with high concentrations of the hardness-causing ions.
