How pH Levels Enter Groundwater in the AR Aquifer
Natural and environmental factors affect pH
pH measures acidity or alkalinity in water, influenced by soil composition, organic material, and rainfall. In the AR aquifer, local geological formations contribute minerals that can shift pH up or down. Acidity can increase from natural decomposition or acid rain, causing corrosive conditions.
Human activity can alter pH too
Land use, agricultural runoff, and waste disposal affect aquifer chemistry. These inputs can lower pH in groundwater wells sampled in this region, contributing to corrosivity risks.
Interpreting Certified Laboratory pH Test Results
Understanding concentration versus range
Laboratory tests report pH as a number from acidic (below 7) to alkaline (above 7). A single test reflects the water at the time and place sampled. Only a certified lab test of your own water can determine your home's exact pH.
Relevance of secondary standards
The Environmental Protection Agency sets a secondary standard for pH in water at 6.5 to 8.5. This is based on aesthetic factors and corrosivity, not health risks. The AR aquifer samples showed a median pH of 7.1 with some results below 6.5, indicating occasional acidity.
Impact of Sample Depth and Well Type on pH Expectations
Variability with well depth
Shallow wells often experience more surface influence and may show more acidic pH. Deeper wells can have more stable mineral balances. The 64 wells sampled varied in depth, contributing to the pH range observed.
Differences by water source type
Groundwater from aquifers like AR's can differ greatly in pH compared to surface water sources. Understanding your source type helps set expectations for water chemistry and potential corrosive effects.
Meaning of 'Detected', 'Median', and 'Range' in USGS Sampling Records
Detected means measured, not problematic
All 97 samples detected pH within measurement limits—this is normal and expected as pH exists in all water. Detected is not a health or safety violation.
Median is the middle value of measurements
The median pH of 7.1 suggests typical groundwater in this aquifer is near neutral, with balanced acidity and alkalinity.
Range shows variability
The range from 5.8 to 8.3 indicates some water samples were more acidic than the EPA secondary standard’s lower aesthetic threshold. This implies occasional conditions for corrosive water in the area but not necessarily in all wells.
Fixtures and Appliances Most Sensitive to Corrosivity
Metal pipes and fittings show early signs
Corrosive water tends to degrade copper, galvanized steel, and iron pipes first, causing pinhole leaks or stains.
Water heaters and faucets affected by acidic pH
Lower pH water accelerates wear on heating elements and faucet components, leading to reduced lifespan and increased maintenance.
Appliances with internal plumbing
Dishwashers, ice makers, and washing machines may experience corrosion-related failures due to acidic water if untreated.
Single Test to Confirm Corrosivity at Your Home
Order a comprehensive pH test from a certified laboratory
Testing your own well or tap water provides specific data needed to determine corrosivity for your residence. Results below 6.5 standard units indicate acidic conditions that may require treatment.
Choosing treatment based on test results
For confirmed corrosive water, the Autotrol Corrosive Water Damaging Pipes Filter ships ready to configure and can reduce corrosive effects on plumbing. Its proven technology addresses acidic water problems documented in regional groundwater.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2024-08-02. These figures describe groundwater sampled in this area. They are not a test of any individual private well - only a test of that well can establish its own water.
On record: U.S. Geological Survey sampling of pH in the aquifer (FIPS ): 97 results from 64 wells, median 7.1 standard units, range 5.8-8.3 standard units; EPA secondary standard for pH is 6.5-8.5 (aesthetic/corrosivity, not health-based); 7 of 97 sampled results fell below 6.5
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