What pH is Rainwater?
Rainwater's pH is typically slightly acidic, ranging from approximately 5.0 to 5.6. This slight acidity is due to the absorption of carbon dioxide from the atmosphere, forming carbonic acid.
Several factors can influence the exact pH of rainwater:
- Atmospheric CO2: The primary factor determining rainwater's acidity is the level of carbon dioxide in the atmosphere. Higher CO2 levels lead to more carbonic acid formation and thus a lower pH.
- Pollution: Industrial emissions of sulfur dioxide and nitrogen oxides can significantly lower the pH, resulting in acid rain. This type of rain has a pH below 5.0.
- Location: Geographic location and local pollution sources impact the composition and pH of rainwater. Urban areas tend to have more polluted rainwater compared to rural areas.
- Measurement methods: Different measurement techniques and the accuracy of the equipment used can influence the recorded pH values. The age of the sample can also impact pH.
Examples of Rainwater pH Readings from Various Sources:
Several sources report varying pH readings, highlighting the influence of local conditions and measurement techniques.
- Some readings indicate a pH between 5 and 6. (Hortographical)
- Other sources cite a range of 5.5 to 6. (MyWaterFilter)
- A pH of 5.7 is mentioned as typical in some regions. (MarriedToPlants)
- However, readings above 7 have also been reported, suggesting contamination. (Houzz, Slippertalk Orchid Forum)
Understanding pH and its Significance
pH measures the acidity or alkalinity of a solution. A pH of 7 is neutral. Values below 7 are acidic, and values above 7 are alkaline. Slight variations in rainwater pH are typically normal, but significant deviations can indicate pollution.
