Question

Which factors might cause the pH of the water to change? Check all that apply.

rain

water depth

temperature change

water filter

Answer 1

All of them can affect water pH.

- Rain: rainwater carries dissolved CO2 and pollutants (acid rain) that can lower pH when it enters a body of water.
- Water depth: depth often correlates with different chemistry (less mixing, different temperature, oxygen depletion and decomposition at depth) that can raise or lower pH.
- Temperature change: temperature affects gas solubility and dissociation equilibria (e.g., CO2/H2CO3, water ionization), so pH changes with temperature.
- Water filter: some filters remove or add ions (ion-exchange, reverse osmosis, alkaline cartridges, etc.), which can change pH depending on the filter type.