Contaminant Unit: mg/L

Nitrate

A nitrogen compound that can enter water from agricultural runoff, fertilisers, and septic systems.

ADWG Guideline

50 mg/L

Nitrate (NO3-) is a naturally occurring form of nitrogen. In drinking water, elevated levels usually come from agricultural fertiliser runoff, animal waste, or malfunctioning septic systems.

Why it matters

The ADWG sets a guideline of 50 mg/L (as nitrate). The primary health concern is:

  • Infant methemoglobinemia (“blue baby syndrome”): Babies under 3 months are most at risk. Nitrate interferes with the blood’s ability to carry oxygen.
  • Adults can tolerate higher levels without acute effects
  • Long-term exposure to elevated nitrate is being studied for potential links to certain cancers

Australian context

Urban treated water rarely has elevated nitrate. It is more commonly a concern in:

  • Rural bore water near agricultural land
  • Private water supplies without regular testing
  • Areas with intensive livestock or horticultural operations

Related Terms

ADWG (Australian Drinking Water Guidelines) E. coli

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Disclaimer: Glossary definitions are provided for general educational purposes only and do not constitute medical advice or professional guidance. For specific health concerns about your drinking water, consult a qualified health professional. See our Terms of Use.