Blue-green stains and pinhole leaks in copper: acidic well water

Blue-green stains in a tub, a turquoise ring under a dripping faucet, and pinhole leaks that appear in copper for no reason are all one problem: acidic well water. Groundwater in Henderson County’s granite and gneiss commonly runs pH 5.5 to 6.5, and water that acidic dissolves copper. Test for $50 to $250, then install an acid neutralizer at $1,200 to $2,500. Repiping without treating the water simply buys another twenty years of the same failure.

Check this first

1. Look at where the stains are. Under a dripping faucet, in the tub below the shower head, in a toilet tank, on white porcelain everywhere water sits. Uniform blue-green across the whole house means the water. A single stained fixture usually means a leaking valve.
2. Check the pinholes. Acid attack from the inside makes small round holes with a bright, clean edge and a green crust around them. Holes that appear at the same spot on several lines, especially horizontal runs, are the signature.
3. Look at the water heater. Acidic water shortens heater life and eats anode rods fast. A heater that failed early is corroborating evidence.
4. Test. Ask for pH and copper. Everything after that follows from those two numbers.

What is usually wrong

Testing and treatment prices are on the pricing page and explained on the testing and treatment page.

Why the water here is acidic

Henderson County has no limestone to speak of. In limestone country rainwater dissolves a little calcium carbonate on the way down and arrives at the well neutral and hard. Under the Blue Ridge there is nothing to dissolve: the U.S. Geological Survey’s Ground Water Atlas describes these aquifers as fractured crystalline bedrock, gneiss, schist, and granite, under a weathered blanket. Rain is already slightly acidic from dissolved carbon dioxide, it picks up more from decaying leaf litter in the soil, and nothing in the rock buffers it back. The USGS assessment of the Piedmont and Blue Ridge crystalline-rock aquifers found nuisance constituents, low pH among them, across roughly half the study area.

The result is universal here, not a local quirk. The same chemistry shows up in Flat Rock, Etowah, Edneyville, Laurel Park, and out into Transylvania and Polk counties around Brevard and Columbus. Houses on city water do not see it because the City of Hendersonville adjusts pH at the plant. Your well does not.

What a neutralizer actually does

Water is fed up through a tank of calcium carbonate media, or a calcite and magnesium oxide blend for water in the low 5s. The media dissolves slowly and raises pH into the 7s. Two consequences worth knowing before you buy: the water gets slightly harder, because the calcium that neutralizes the acid stays in it, and the media is consumed, so it needs topping up on a schedule that depends on your pH and your usage. A backwashing model keeps the bed from packing and needs a drain nearby; an upflow model does not backwash and is simpler. That choice, plus tank size, is what moves the price across the $1,200 to $2,500 range.

Do not treat pH by guesswork. Overshooting causes scale, and an oversized system on a low-yield well can cost you pressure. Size it from the test.

Order of operations

1. Test first. pH and copper, plus the rest of the panel if you have never tested this well.
2. Neutralize. Then let the system run for a few weeks.
3. Retest to confirm the pH is where it should be.
4. Then repair the plumbing. Fix or replace the runs that have already failed. Doing this step first is the expensive mistake, and it is an easy one to make in older houses.

When to call

There is no emergency in a stain. Call promptly if pinhole leaks have started, because those multiply, and every one of them is a water damage claim waiting to happen inside a wall. Call the same day for an active leak. If you are buying a house on a well in this county, put pH and copper on the test list before closing; the blog post on selling a house on a well covers what buyers and lenders ask for.

What to expect on the call

Bring the lab result if you have it. If you do not, the testing page covers what to order and from whom, because nobody should price treatment equipment off a photo of a bathtub. On site the tech should look at pH, hardness, and iron, check the pipe material and the heater, and size the neutralizer to your household and your flow rate. Get the number in writing before anything is installed.