composition

• rainwater contains dissolved carbon dioxide and oxygen
• carbon dioxide lowers the pH of rainwater and makes it slightly acidic
• Groundwater contains dissolved ions such as calcium , magnesium , potassium and sodium
• The ions in groundwater are part of minerals that dissolve in the water as it passes over rock -> could contain pollutants , pesticides , household + industrial waste
• natural pollutants sunch as bacteria and viruses can also be present in groundwater