Minds → Water & Wastewater → What are the maximum contaminant levels for inorganic contaminants like arsenic and nitrate under 40 CFR 141.62? Answer in under 100 words.

US FederalCode of Federal Regulations

What are the maximum contaminant levels for inorganic contaminants like arsenic and nitrate under 40 CFR 141.62? Answer in under 100 words.

Under 40 CFR 141.62, the maximum contaminant level for arsenic is 0.010 mg/L and for nitrate it is 10 mg/L as Nitrogen. These levels apply to community water systems and non-transient, non-community water systems.

Last verified: 2026-08-26 · Sources checked: 1/1 resolving · Next scheduled review: 2026-11-24

Details

40 CFR § 141.62(b) establishes specific maximum contaminant levels (MCLs) for inorganic substances. Arsenic has an MCL of 0.010 mg/L. Nitrate has an MCL of 10 mg/L as Nitrogen. The regulation also identifies Best Available Technologies (BATs) for achieving compliance, such as coagulation/filtration, ion exchange, and reverse osmosis.

Numbers & thresholds

Contaminant	MCL
Arsenic	0.010 mg/L
Nitrate	10 mg/L (as Nitrogen)

Exceptions & edge cases

The MCL for arsenic only applies to community water systems. The MCL for nitrate applies to community water systems, non-transient non-community water systems, and transient non-community water systems.

Sources

[1]U.S. National Archives, Electronic Code of Federal Regulations — 40 CFR 141.62 — Maximum contaminant levels for inorganic contaminants · as of 2026-08-26

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