Nitrate in Water

A fertilizer-linked compound that seeps into groundwater.

Nitrate occurs naturally, but modern levels in water usually trace to fertilizer runoff and septic leakage. Its most serious risk is specific: in infants under six months, excess nitrate interferes with the blood’s ability to carry oxygen — the condition known as blue baby syndrome. Private wells in agricultural areas are the classic setting.

What it is

Nitrate is a nitrogen compound used heavily in fertilizers and produced by decomposing organic matter. It’s tasteless, odorless, and invisible in water — testing is the only way to detect it.

How it gets into water

Agricultural runoff, septic system leakage, and erosion of natural deposits are the main routes. Shallow wells and wells near farmland or livestock operations are most vulnerable, and levels can spike seasonally after heavy rain or fertilizing.

What a result can tell you

The EPA limit is 10 mg/L. Results above it mean the water shouldn’t be used for infant formula or drinking by pregnant women — and boiling makes it worse, not better, by concentrating the nitrate. A high reading calls for lab confirmation, a check of nearby sources, and treatment such as reverse osmosis or ion exchange if confirmed.

What it can’t tell you

A strip can’t identify where the nitrate is coming from, and one normal result doesn’t cover the seasons — well owners should test at least annually, and after flooding or nearby agricultural changes. If an infant has been fed formula made with high-nitrate water and shows bluish skin coloring, seek medical care immediately.