Nitrate in well water
Nitrate comes from fertilizer, manure, and septic systems. You can't taste or see it. High levels are a particular danger for babies under 6 months, so test before using well water to mix formula.
Boiling does not remove nitrate. It actually concentrates it as water evaporates. If your level is high, use bottled water for drinking and formula until it's treated.
The safe level
The EPA limit is 10 mg/L (reported as nitrate-nitrogen). Many lab reports list it as "Nitrate-N" or "Nitrate+Nitrite N."
How common it is
It depends a lot on how much farmland is nearby. Statewide, about 4% of Penn State well tests were over the limit, but in heavily farmed counties it's far higher: about 1 in 4 Lancaster County samples. See how your county compares.
Who is most at risk
- Infants under 6 months. High nitrate can cause "blue baby syndrome," which reduces the blood's ability to carry oxygen. Never use high-nitrate water for formula.
- Pregnant women are commonly advised to avoid high-nitrate water too.
What to test for
Penn State's Agriculture / Septic package (WD04, $70) adds nitrate to the standard bacteria test. If your well is near fields or a septic system, test every year. Levels often change with the seasons, so a second test in spring after fields are fertilized is useful.
Common fixes
| Your situation | Usual fix |
|---|---|
| Nitrate over the limit, drinking and cooking water only | A reverse osmosis system at the kitchen sink. This is the most common and affordable fix. |
| High nitrate and you want the whole house treated | A whole-house anion exchange system, similar to a water softener but with a different resin. |
| Nitrate rising over time | Look at the source: septic system condition, how close fields or animals are to the well, and whether the well cap and casing are sealed. |
When to call a professional
If your nitrate is above 10 mg/L, have a water treatment professional recommend a system, and retest after installation. Reverse osmosis filters need regular changes to keep working.
Get a free in-home water screening
One trusted local company checks your water at home and gives you a written quote. Free, with no obligation.