Glossary · Health & indoor air
Nitrate (well water)
Also called: nitrates · nitrite · nitrate-nitrogen
A chemical from fertilizer, manure and sewage that can seep into wells; high levels are dangerous for babies, so test well water for it.
What it means
You can't see nitrate in water, so only a lab test shows the level. Infants are most at risk: high levels reduce the blood's ability to carry oxygen, a condition known as blue baby syndrome. Wells near fields, livestock or septic systems are more likely to be affected.
Why it matters in an audit
If a baby or pregnant person lives in the home, a nitrate test belongs alongside the regular bacteria test, especially in farm areas.