Blue-green stains and corrosive well water
Blue-green stains mean your water is corrosive, usually because its pH is low (acidic). It slowly dissolves copper and sometimes lead from your plumbing. That's why it's worth fixing even though the water itself may look fine.
Signs to look for
- Blue-green stains in sinks, tubs, and under faucets
- A bitter or metallic taste, especially first thing in the morning
- Pinhole leaks in copper pipes
- Water heaters and fixtures wearing out early
How common it is in Pennsylvania
Very common. In Penn State's well tests across the state, about 2 in 3 samples were corrosive and about 1 in 6 had a pH outside the normal range. Some counties run much higher: more than half of Carbon County samples had low pH. See how your county compares.
What causes it
Some groundwater is naturally acidic and low in minerals, especially where it runs through sandstone and shale rather than limestone. Old mining activity can add to the problem in some areas.
What to test for
Test pH, corrosivity, copper, and lead, including a "first-draw" sample of water that sat in the pipes overnight. Penn State's Aesthetics + Lead package (WD03) covers all of these. Normal pH is 6.5 to 8.5.
Common fixes
| Your situation | Usual fix |
|---|---|
| Slightly acidic (pH in the low 6s) | A calcite neutralizing filter where water enters the house. It slowly dissolves to raise the pH, and needs refilling about once a year. |
| Very acidic (pH below about 6) | A small pump that feeds a neutralizing solution, such as soda ash, into the water. |
| Lead or copper found while you wait for a fix | Run the cold tap until it feels noticeably colder before drinking or cooking, and use cold water for cooking. |
Neutralizers can make water slightly harder. Fix the pH before adding iron or manganese filters, because many of them need normal pH to work.
When to call a professional
If lead shows up in your test, or your pH is below 6, get a professional recommendation. If you have young children or someone in the home is pregnant, use bottled water for drinking until lead is fixed and retested.
Get a free in-home water screening
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