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Did you know that rainwater is slightly acidic and, in some cases, can be very acidic? This can cause acidic groundwater and might cause your well water to be corrosive to plumbing, fixtures, and appliances. Fortunately, there are simple ways to neutralize acidic well water and protect your home.
Acidic well water is commonly caused by acid rainfall due to atmospheric carbon dioxide and other airborne pollutants and, in some cases, runoff from mines.
Pure water has a pH of 7.0 (neutral); however, natural, unpolluted rainwater has a pH of about 5.6 (acidic). The acidity of rainwater comes from the natural presence of three substances (Carbon dioxide, nitrogen oxide, and sulfur dioxide): CO2, NO, and SO2. CO2 is present in the greatest concentration and therefore contributes the most to the natural acidity of rainwater. As CO2 levels rise, acid rain might be increasing as well.
Hello, and thanks so much for tuning in again to the Clean Water Made Easy Podcast. I’m Gerry Bulfin. I’m a Water Treatment Contractor and WQA-certified Master Water Specialist. I hope you’re having a great day wherever or however you’re listening.
Today’s episode is all about acid well water. It’s very common. We’ll also cover acid rain and acidic spring water, which are often used in private water systems.
One of the most common causes of pipe and fixture corrosion is low pH—meaning acidic water. If the pH is less than 7, it’s considered acidic. The pH scale runs from 1 to 14; 7 is neutral.
I’ll explain how copper corrosion from acidic water occurs, how to slow it down, and how to eliminate blue stains (a clear sign of copper corrosion).
We’ll cover the main systems used to treat low pH:
A common source is acid rain, mostly caused by atmospheric carbon dioxide. CO2 levels are rising, so rainfall is more acidic. Natural, unpolluted rainwater has a pH of about 5.6.
Once rainwater becomes groundwater, its acidity depends on the surrounding geology. If groundwater flows through limestone, it’s often neutralized. But granite or sand doesn’t buffer pH, so the water stays acidic.
Corrosion is the chemical or electrical degradation of metal in contact with water. Acidic water (pH < 7) is more corrosive than alkaline water.
Even homes with repiped systems may still experience corrosion if small pipe sections remain. Acidic water easily eats through these areas.
The most common and effective solution is a calcite neutralizer. Calcite is a natural form of calcium carbonate that dissolves into the water to raise its pH. It’s best for pH levels between 6.0 and 6.9.
For lower pH levels (5.0 to 6.0), we use a blend of calcite and magnesium oxide (Corosex or Flowmag).
Neutralizer systems come in two types:
To choose the right system, test your water for:
A pH test on-site is recommended, as CO2 in water can skew lab results. Use this data to determine which system is best for your water.
This system from Clean Water Store uses high-purity calcite (calcium carbonate) media to gently raise low pH (6.0–6.9) groundwater and help prevent copper corrosion. It features a user-friendly manual backwash valve and top-fill access for easy media replenishment, all built with durable construction for long-lasting performance.
Backwash systems offer better performance and sediment filtration. They clean themselves automatically and help minerals dissolve more efficiently.
Upflow systems are more affordable and easier to install, but don’t filter as well and can cause flow problems if not properly flushed after adding minerals.
Both systems work for pH between 5.0 and 6.9. Below pH 5.0, consider soda ash.
Neutralizers slightly increase water hardness, but often not enough to be an issue. Many customers find their water is still pleasant to use, and it helps protect pipes from further corrosion.
If needed, a water softener can be added after the neutralizer.
Neutralizers are sized based on flow rate (gallons per minute). A typical system lasts about a year before media needs to be added. Keep the tank two-thirds full.
Check every 6–12 months. If the tank runs dry, blue stains will return.
Read more:
If your pH is below 5.0, soda ash injection is more effective. Soda ash (sodium carbonate) is mixed with water and injected using a metering pump.
It’s adjustable and works well for:
It does add some sodium, so it’s not ideal for those on low-sodium diets. But it’s reliable, adjustable, and effective.
Read more: Acid Neutralizer vs. Soda Ash for Well Water: Which One Do You Need?
To monitor effectiveness, test copper levels monthly during the first year. A first-draw test (after water sits overnight) is best. Most cases of copper corrosion are resolved once the pH is neutralized.
Make sure to check your system periodically and keep the media topped up.
Read more:
In this episode, we covered:
Thanks for listening!
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