NOM-001-SEMARNAT-2021
This is an Official Mexican Standard issued by SEMARNAT that sets the maximum permissible limits of pollutants in wastewater discharged into national receiving bodies, such as rivers, lakes, seas, and soils. The purpose of this standard is to protect water quality and prevent environmental and health impacts.
Main changes compared to NOM-001-1996
- New classification of receiving bodies
Categories A, B, and C are eliminated. Now bodies of water are classified by type: - Rivers, streams, canals, and drains
- Reservoirs, lakes, and lagoons
- Mexican marine zones
- Soils
- Removed parameters
The following are eliminated: - BOD5
- Floating matter
- Settleable solids
- Fecal coliforms
- New parameters incorporated
- COD (Chemical Oxygen Demand)
- TOC (Total Organic Carbon)
- E. coli and fecal enterococci
- Acute toxicity
- True color
- Stricter limits
Lowered permissible levels of: - Fats and oils
- Total suspended solids
- Total nitrogen
- Total phosphorus
- Maximum allowed temperature
Reduced from 40 °C to 35 °C.
Effective date
- Publication: March 11, 2022
- Effective: From April 3, 2023
- Deferred parameters: Acute toxicity and true color will be mandatory starting in 2026.
Testing methods and obligations
- Specific measurement methods such as:
- NMX-AA-003-1980 for sampling
- NMX-AA-005-SCFI-2013 for fats and oils
- Companies with discharges must:
- Implement monitoring plans
- Submit periodic reports to authorities
Do you discharge wastewater and need to comply with NOM-001-SEMARNAT-2021? At airCO2 we help you interpret the requirements, evaluate your current parameters, and design a tailored compliance plan.