What a Certified Laboratory Test for pH Reports and How to Read It
A certified laboratory test for pH measures the acidity or alkalinity of water, expressed as standard units typically on a scale from 0 to 14. Values below 7 indicate acidic water, while values above suggest alkalinity; 7 is neutral. The report commonly shows the pH value as a single number, sometimes with a range if multiple samples are analyzed. For Johnson County's aquifer 111ALVM, reported median pH values range from 6.7 to 8.0 standard units across sampled wells. Importantly, the U.S. Environmental Protection Agency’s secondary standard for pH is from 6.5 to 8.5, a range designed to address aesthetic issues and corrosion potential but not health risks. Understanding your water's pH requires comparing your home's test results with these benchmarks rather than with regional data alone.
How pH Enters Groundwater or the Distribution System in Johnson County
In Johnson County, the pH levels in groundwater reflect natural geochemical conditions and interactions with soils and aquifer materials in aquifer 111ALVM. Water passes through mineral layers which can influence its acidity or alkalinity, while agricultural practices and environmental factors may also contribute. The variation of pH from 6.7 to 8.0 standard units in sampled wells indicates a natural range rather than a fixed condition. Water distributed for household use typically reflects these groundwater characteristics unless modified by treatment processes or infrastructure. Recognizing this origin helps clarify that pH is a dynamic measure influenced by local environmental factors rather than a static value anchored to a single source.
What 'Detected', 'Median', and 'Range' Mean in the Sampling Record on This Page
The U.S. Geological Survey’s record for Johnson County’s aquifer 111ALVM shows pH 'detected' in all 10 samples taken from 4 wells between 17 and 177 feet deep, sampled from June 2011 through August 2017. 'Detected' simply means that pH was measured and reported, not that a violation or problem exists. The 'median' value of 7.25 standard units represents the middle pH measurement from all samples, indicating a slightly alkaline nature was most typical. The 'range' from 6.7 to 8.0 standard units demonstrates that pH levels fluctuate among wells and over time within this specific area. These terms describe the characteristics of sampled water broadly, not your individual household water condition.
The Household or Facility Symptoms That Do and Do Not Point to This Problem
Signs that your household water might be corrosive include metal fixtures developing corrosion, blue-green stains on plumbing components, and premature deterioration of pipes or appliances. Water with pH levels below about 6.5 tends to be acidic and more likely to cause such issues. Symptoms unrelated to water corrosivity, such as cloudy water, unusual odors, or discoloration without plumbing damage, suggest other water quality factors. Since Johnson County aquifer samples consistently show pH within the EPA’s secondary standard, household corrosion symptoms should prompt specific water testing to confirm corrosivity before assuming it is present.
How Seasonal or Multi-Year Variation Shows in the Record (Dates and Ranges Given)
The sampling for Johnson County aquifer 111ALVM occurred over a six-year span from June 2011 to August 2017. This extended timeframe includes seasonal shifts and year-to-year variability in groundwater pH levels due to factors such as rainfall, temperature, and aquifer recharge. Despite these potential influences, the pH values remained within the range of 6.7 to 8.0 standard units without falling below the 6.5 threshold linked to corrosive conditions. This stability suggests that while pH can vary, significant acidification episodes have not been recorded in sampled wells over multiple years.
Deciding if your household water is corrosive requires testing your specific water because regional data cannot replace well-specific analysis. If corrosive water is confirmed by test results, the Fleck Corrosive Water Damaging Pipes Filter ships ready to configure for neutralizing acidity and protecting plumbing systems. Understanding the regional pH range, sources, and symptoms helps guide the correct steps toward ensuring your household water does not damage pipes or appliances.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2017-08-28. 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 111ALVM aquifer (Johnson County): 10 results from 4 wells, median 7.25 standard units, range 6.7-8.0 standard units; EPA secondary standard for pH is 6.5-8.5 (aesthetic/corrosivity, not health-based); 0 of 10 sampled results fell below 6.5