What Causes High Alkalinity in Water?

iPhoto by Tessa Watson (License: Creative Commons Attribution)

Water is the most important liquid for sustained life because of its neutral pH of 7. It replenishes the supply of liquids lost through sweat and urine without changing our chemical balance. Alkalinity in water is preferable to acidity; with all the pollutant sources of industry and transportation, acid rain is on the rise, and high water alkalinity acts as a buffer to neutralize excess acidity. Recognizing the relationship between water, alkalinity and our ecosystem can help us better understand the delicate balance of our environment.

Alkalinity and pH Balance

The pH of a solution measures the concentration of hydrogen ions; a pH measurement refers to how acidic or basic a solution is. The higher the concentration of hydrogen ions, the more acidic a solution is. The pH scale is a spectrum that goes from highly acidic, represented by 0, to highly basic or high alkalinity, represented by 14. Water has a natural pH balance that is normally around 7, or neutral. Living organisms require a pH balance between 6 and 9.

Causes of Alkalinity

Alkalinity in a solution means the solution is capable of buffering acidic solutions with higher concentrations of hydrogen ions. Alkalinity in water comes from a high concentration of carbon-based mineral molecules suspended in the solution. Water with high alkalinity is said to be "hard." The most prevalent mineral compound causing alkalinity is calcium carbonate, which can come from rocks such as limestone or can be leached from dolomite and calcite in the soil. Water treatment plants can be treated to a higher alkalinity.

Acid Rain

Acid rain is a wet deposition that contains abnormally high amounts of nitric acids and sulfuric acids, and therefore hydrogen ions. Most acid rain comes from man-made sources, especially fossil fuel combustion. Natural sources, such as volcanoes and rotting vegetation, can also cause acid rain. As acid rain falls into a solution, that solution's pH decreases and becomes more acidic. Acid rain won't burn human flesh, but can reduce the pH of an ecosystem below the point at which it can sustain life. High alkalinity or alkalinity treatment is needed in areas facing consistent acid rain, as alkalinity in water acts as a buffer and stabilizes water's pH balance closer to 7.

Alkalinity Testing

If your water comes from public treatment plants, you don't need to worry about testing for acidity. However, if your home uses groundwater or well water, you may want to make sure your drinking water is in the correct alkalinity range. Drinking water supply tests can be obtained from the local health department. Fresh drinking water should have an alkalinity level of 20 to 200 milligrams of calcium carbonate per liter of water.

High Alkalinity Damage

Although more people are aware of the concerns of excess acidity in water, excess alkalinity can also be harmful. Excess minerals suspended in water causes turbidity, a fogging up of clear water due to suspended particles. Hard water can facilitate the transfer of lead in pipes to water, putting our health at risk. Washing with hard water can leave the skin dry and itchy. Excess alkalinity in an ecosystem can reduce that ecosystem's ability to sustain life.