Nitrates & Nitrites
What is Nitrates & Nitrites?
Nitrates and nitrites are compounds that enter drinking water mainly through agricultural fertilizer runoff, septic systems, and wastewater discharge. They're more common in agricultural areas and in homes on private wells, but they can appear in municipal supplies too.
Health effects
High nitrate is especially dangerous for infants: it can interfere with the blood's ability to carry oxygen, a condition known as “blue baby syndrome.” Longer-term, elevated nitrate exposure has been studied for possible links to certain cancers, which is why health-based guidelines sit well below the federal legal limit.
In DC-metro tap water
If your home is on a private well or near agricultural land, nitrate is worth checking specifically. Well water isn't covered by municipal testing, so the responsibility falls on the homeowner.
How to remove it at the tap
Standard carbon filters do not remove nitrate. Reverse osmosis is one of the few point-of-use technologies proven to reduce nitrate and nitrite effectively, making it the go-to solution for affected homes.
Where Nitrates & Nitrites shows up locally
Local water reports where this contaminant class is documented in the utility's data or watershed. Open your area to see the specifics and look up your exact zip code.
Frequently asked
Does a carbon or pitcher filter remove nitrate?
No. Carbon and standard pitcher filters do not reduce nitrate. Reverse osmosis is the reliable point-of-use option.
Should I test my well water for nitrate?
Yes. Private wells aren't covered by municipal testing, and nitrate is a common well contaminant. Annual testing is recommended, especially if there are infants in the home.
Does reverse osmosis remove nitrate?
Yes. Reverse osmosis is proven to reduce both nitrate and nitrite at the tap.
Related guides
The gap between what's legal and what's healthy
A utility can pass every federal test and still deliver water far above the levels health scientists consider safe. Federal legal limits were largely set decades ago; the health-based guidelines below reflect current cancer- and development-risk research.
Federal law allows 71× the health guideline
Sources: EPA National Primary Drinking Water Regulations (legal limits) and the EWG Tap Water Database / state public-health goals (health-based guidelines). A reverse osmosis system reduces every contaminant above at the point of use.