What Is Alkalinity in Water?

The pH levels in water determine if the source is more acidic or alkaline. The alkaline level of water relates to its ability to neutralize acid.

The Balance Between Acidic and Alkaline

• A moderate percentage of alkalinity helps balance the less desirable effects of acid. Although most don't consider water corrosive, water (for example, some of the springs at Yellowstone Park) can have a high degree of acidity--and be as acidic as battery acid. Fresh water, though, is generally more balanced with alkalinity levels of 20-200 mg/L.

Hard Water

• However, when water becomes too alkaline, it may taste like soda and could have a drying effect on the skin. Moreover, it becomes what is termed "hard water." If it seems a soda-like water should be soft, consider the sources of those ions that contribute to making a water hard. Carbonate rocks, such as limestone, are the main sources to turning water alkaline.

A Buffering Solution

• Calcium carbonate and other such carbonate compounds provide ions to the buffering system. Without a buffering solution, acid introduced in the water could alter the concentration of available hydrogen (H+). This buffer protects aquatic wildlife from rapid changes in pH levels.

Ions for Alkalinity

• Fortunately, numerous ions in water provide for a buffering solution to acid. Natural alkalinity may be due to the presence of numerous ions, including hydroxides, carbonates or bicarbonates.

Too Much Alkalinity

• But when water (especially drinking water) becomes too alkaline, treatments, such as reverse osmosis, distillation and deionization, are used to remove excessive amounts of minerals.