The test for pH determines the acidity or alkalinity of a substance and is measured on a theoretical scale ranging form 0 to 14. A pH of 7 indicates that a substance is neutral, therefore, it is neither acidic or alkaline. Acidity increases as you move down and away from the neutral point on the scale. As a result, the lower the number, the greater the acidity. For example, a pH of 3 is more acidic than a pH 6. In contrast, alkalinity increases as you move up the pH scale away from the neutral point of 7. The higher the number, the greater the alkalinity. It is recommended that the pH of private well water be between 6.5 and 8.5.
Effects of Acidity
Generally, acidic water does not directly present a health risk. It may wreak havoc on your plumbing system, however. Acids are corrosive, and over time, acidic well water will corrode pipes and any other metal water system components through which it flows. One of the most common causes of corrosion in private water systems is acidic water. Water acidity does become a health concern if certain metals, such as lead, enter the water as a result of acidic leaching of the pipes.
One method of correcting well water acidity involves the use of neutralizing filters. Neutralizing filters are tanks that contain alkaline granules such as calcite (calcium carbonate, lime or marble) or magnesia (magnesium oxide). As water from the well passes through the alkaline granules, a chemical reaction occurs that neutralizes the water. Unfortunately, the calcium or magnesium added to the water during the process hardens the water and causes lime scaling of plumbing components. Water softeners are then needed to counteract water hardness. Neutralizing filters are effective for treating water with a pH as low as 6.
Chemical Injection System
For well water with a pH less than 6, a chemical-feed pump is required to inject soda ash (sodium carbonate) directly into the water supply. Each time the well pump turns on, a chemical-feed pump adds a soda ash solution to the water. This mixture then goes to a retention tank, where the neutralization process occurs. The chemical injection system is costly and labor-intense when compared to neutralizing filters. Well water with a pH less than 4 requires the use of caustic soda (sodium hydroxide) rather than soda ash as a neutralizing agent.
Water pH is only one of many factors influencing well water quality. Well water should be tested once a year for total coliform bacteria, nitrates and total dissolved solids, as well as pH. Most local health and environmental departments will perform such tests. More extensive well water testing should be performed by a state-certified laboratory. Your local health or environmental agencies should be able to provide you with a list of such facilities in your area.