10 drops of phenolphthalein indicator into each sample was added and if no pink colour is seen, added N/44 solution hydroxide from a burette to the sample and stir gently until a slight permanent pink colour appears as compared with the distilled water. The following formula was used to calculate CO2 of the waters, CO2mg/l = ML of N/44 ×10 and the data was recorded the ml of sodium hydroxide used