Nitrate is the one that usually arrives from the surface.
What it is
Nitrate is a nitrogen compound that reaches groundwater from fertilizer, manure, and septic systems rather than from rock. It is reported as nitrate-nitrogen in milligrams per liter, and the EPA standard is 10. Shallow wells, dug wells, and wells with poor casing seals near cropland or a septic field usually carry more of it.
What it usually does
Nothing detectable. It has no taste, smell, or color at any level. It is the one contaminant on this list with an acute rather than a long-term concern, specifically for infants under six months, and that is a conversation for a doctor and the county health department rather than for us.
What it does not prove
Nitrate varies with the season and with rainfall, so a single low reading in a dry month usually does not describe the same well in spring after fertilizer goes down. A nitrate result also does not cover bacteria, although the two often move together, since both usually indicate surface water reaching the well.
When to test
Usually tested annually on a private well, and usually tested together with coliform bacteria since both speak to the same question of surface influence. Spring, after the ground has taken on water, is usually the more revealing time to draw it. Never boil water to deal with nitrate: boiling concentrates it rather than removing it.
See what this usually means for your water.
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