Which human or natural factors cause a change in ph levels

1. Carbon dioxide concentration  in water  - As CO2 concentration increases, the pH level decreases. In turn, as CO2 concentration decreases, the pH level increases.

2. Acid rain - Acid rain enters the water source and raises acidity of the water, lowering the pH

3. Dissolved Minerals - Dissolved minerals from groundwater areas with limestone bedrock deposits will increase alkalinity by raising the pH.

4. Temperature
Temperature and pH of water also have an inverse relationship. As temperature increases, the pH level decreases; and as temperature decreases, the pH level increases.

5. Waste water
Waste water from individuals, industries and communities can contain traces of cleaning agents, chemical detergents or other contaminants which raise the pH of water.