Well water is not uniformly alkaline, acidic, or neutral; its pH level varies significantly based on the specific geology of the location. Whether well water is alkaline depends entirely on the minerals and gasses dissolved into it as it travels through the ground. Understanding the pH level of a private well is important for any homeowner, as this characteristic directly impacts plumbing integrity and water quality. The relationship between acidity, alkalinity, and the water’s ability to resist change is a manageable factor in well ownership.
Decoding pH and Alkalinity
The measure of acidity or alkalinity in water is known as pH, determined by the concentration of hydrogen ions. The pH scale ranges from 0 to 14, where 7 is considered chemically neutral. Water below pH 7 is acidic, while water above pH 7 is classified as alkaline, or basic. The scale is logarithmic, meaning a drop from pH 7 to pH 6 represents a tenfold increase in acidity.
Alkalinity is a different measurement that describes the water’s capacity to neutralize acids, known as its buffering ability. This capacity is primarily due to dissolved compounds like carbonates, bicarbonates, and hydroxides. High alkalinity allows water to resist changes in its pH level when an acid is introduced. While high pH water is often high in alkalinity, the two terms are not interchangeable, as alkalinity measures concentration while pH measures hydrogen ion activity.
Geological Factors Determining Well Water pH
The primary determinant of well water pH is the surrounding geology and the substances groundwater dissolves during its journey. Water that filters through specific types of bedrock can become naturally alkaline. For instance, water passing through carbonate rocks such as limestone or dolomite picks up calcium and magnesium carbonates, which increase the water’s pH and raise its buffering capacity.
In contrast, water that flows through areas with igneous rock, like granite, or through organic-rich soils tends to be more acidic. These environments lack neutralizing carbonates and may instead dissolve acidic compounds. Carbon dioxide naturally present in the soil also combines with water to form weak carbonic acid, which lowers the groundwater’s pH level. The duration and path of the water’s travel also play a role, as longer contact time with mineral deposits means more opportunity for dissolution and subsequent pH changes.
Consequences of pH Extremes for Homeowners
Water that is too acidic, generally below a pH of 6.5, can cause damage to a home’s plumbing system due to corrosivity. This corrosive water gradually dissolves metals from pipes and fixtures, leading to leaks and the leaching of heavy metals like copper and lead into the drinking supply. Visible signs of this corrosion include blue-green stains on sinks and tubs from copper plumbing, or rust-colored stains from iron pipes.
On the opposite end, highly alkaline water, particularly above a pH of 8.5, creates different issues. High pH often correlates with hard water, which causes mineral scale buildup inside pipes, water heaters, and appliances. This scaling reduces the efficiency of water-using appliances and decreases water pressure over time. While not a direct health risk, very high pH water may also impart a slightly bitter taste or a slippery feel.
Testing and Adjusting Well Water pH
Well owners must monitor their water quality, and the first step is accurate testing of the pH level. Home testing kits provide a quick initial check, but a professional laboratory test offers the most accurate results, often including a full analysis of mineral content and alkalinity. The Environmental Protection Agency (EPA) suggests a pH range between 6.5 and 8.5 for drinking water to prevent the negative effects of extremes.
If testing reveals acidic water, the pH can be raised using an acid neutralizer system. This system typically contains a filter media like calcite or a blend of calcite and magnesium oxide, which the acidic water dissolves as it passes through to increase the pH. For very low pH levels, a chemical feed pump injecting a solution like soda ash may be necessary for more precise control. Lowering a high pH is generally less common but can be achieved using a chemical injection system that introduces a weak acid solution. Before installing any treatment equipment, professional consultation is important to select the correct system for the water’s specific chemistry.