The pH measurement is a fundamental indicator of water quality, providing a simple scale to understand its acidity or alkalinity. Measured from 0 to 14, a pH of 7 is considered neutral. Values below 7 indicate increasing acidity, while numbers above 7 signify increasing alkalinity. For homeowners relying on private wells, knowing the pH of their water is necessary, as this characteristic influences taste, plumbing integrity, and the potential for metal contamination.
The Typical pH Range for Well Water
The average pH of well water is highly variable, depending mostly on the local geology and the types of rocks and soil the groundwater interacts with. For most groundwater systems, the typical range falls between 6.0 and 8.5. Water passing through granite regions often has a lower, more acidic pH. Conversely, water flowing through limestone or dolomite aquifers tends to have a higher, more alkaline pH due to dissolving calcium and magnesium minerals.
The U.S. Environmental Protection Agency (EPA) does not mandate pH levels for private wells, but provides a guideline for public water systems. This guideline, classified as a Secondary Maximum Contaminant Level (SMCL), recommends a pH between 6.5 and 8.5. This range is established for aesthetic concerns like taste and to prevent corrosion or scaling in infrastructure. Well owners should use this recommended range as a practical target.
Impacts of Acidic Water
Water with a pH below 6.5 is considered acidic and can be corrosive to household plumbing. This occurs because the water dissolves metals from pipes, fixtures, and appliances, leading to structural damage. A telltale sign is the appearance of blue-green stains on sinks and tubs, which indicates the leaching of copper.
Acidic water can leach heavy metals like lead and copper directly into the drinking supply, compromising safety. Lead is highly toxic and poses severe health problems, especially for children. The corrosive action can also cause pinhole leaks in pipes, leading to costly water damage and premature failure of appliances.
Impacts of Alkaline Water
Water with a high pH, typically above 8.5, is considered alkaline and presents challenges related to mineral deposition. The high concentration of dissolved minerals, often calcium and magnesium, causes scaling, which is a hard buildup on surfaces. This mineral scale can clog pipes, reduce water pressure, and decrease the efficiency of water-using appliances.
Scale formation is detrimental to water heaters, as mineral deposits insulate the heating elements, shortening their lifespan. High pH water may also affect the taste, often described as “soapy” or “soda-like,” and can make coffee taste bitter. Alkaline water is generally less of a health concern than acidic water.
Testing and Treatment Options
Regular testing is the first step to determine the pH of a private well, as water quality can fluctuate. While DIY test strips offer quick readings, the most accurate method involves sending a sample to a state-certified laboratory. Professional lab testing is recommended because it can simultaneously check for heavy metal contamination, a common consequence of low pH.
Treatment for Acidic Water
For acidic water with a pH between 6.0 and 6.5, the most common solution is a neutralizing filter. This system uses a tank filled with crushed marble or calcite chips, which dissolve to add calcium carbonate and raise the pH. For severely acidic water, often below pH 6.0, a chemical feed pump system injects a precise amount of soda ash (sodium carbonate) into the water supply.
Treatment for Alkaline Water
Addressing highly alkaline water requires different treatment strategies. To lower the pH, a chemical feed pump can inject a weak acid solution, such as acetic acid, providing precise control. Alternatively, a specialized ion exchange unit or a whole-house reverse osmosis system can be installed to reduce the high mineral content that contributes to alkalinity and scale formation.