This standard specifies an EDTA volumetric method for the measurement of calcium in groundwater, surface water and drinking water. It is also applicable to urban wastewater and industrial raw water, as long as it does not contain heavy metals in interfering quantities. This method is not applicable to seawater and other types of water with a high salt content, and is applicable to waters whose calcium content is between 2 mg/l and 100 mg/l (0.05 mmol/l 2 .5 mmol/l). For waters containing more than 100 mg/l of calcium, a dilution of the sample must be carried out.