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Well Water dropped from 8.2 to 6.7

It just rained all night and I tested my well water with API and a digital PH pen today and I was shocked when I saw that the PH had plummeted ... totally unexpected. I haven't lived here long enough to know the details, I guess my well is shallow?

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Permalink Reply by David on April 23, 2012 at 10:13pm

Hey Jonathan!

It's all good and nothing to worry about. Surface water pH is between 6.5 and 8.5. Ground water pH is between 6 and 8.5.

It's totally normal for ground water wells to pH bounce after rains. It should level back out in 3 days or so. If it drops to 6.4 then I wouldn't drink it or even mess with it until it returned to normal range. Sudden drops are usually indicative of rain water run off into the well water reservoir and anything below 6.5 indicates nutrients and/or toxins in the water that could cause health problems.

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Permalink Reply by TCLynx on April 24, 2012 at 5:54am

Is this the pH of water drawn from the well? Or the pH of water in the system that just got rained in heavily?

If it was drawn from the well, did you bubble it for several hours before testing the pH?

See if you test the pH right out of the well or pipes or holding tank, the water has been trapped in a place where the CO2 dissolved in it will stay trapped and that will act as a weak acid, if you aerate the water for a while before testing the pH, you will get a more accurate reading of the pH.

My well water will test close to 7 right out of the faucet but once the CO2 escapes, the pH will be up between 8-8.2 most of the time.

Now I've never experienced a real drop in pH of my well water to the extent you say though the real (after outgassing) pH of my well water will fluctuate by season and rainfall but we are probably talking a max fluctuation between 8.4 down to maybe 7.6 on the outside extremes.

If your well water really has dropped to 6.7 (not just because of trapped CO2) I would worry about ground water intrusion into your well. However if you bubble a sample of your water for a day and test the pH again, I expect you will probably find the pH is really much higher and it wasn't actually as extreme a swing.