Mexico Publishes New Official Standard Regulating Wastewater Discharges to Federal Waterways


On March 11, 2022, the Official Mexican Standard titled NOM-001-SEMARNAT-2021 was published (“NOM” per its acronym in Spanish) setting forth new limits allowed for wastewater discharges to federal waterways.  Such NOM updates and replaces Official Mexican Standard NOM-001-SEMARNAT-1996, and will enter into force in stages.

Regarding the NOM’s specifics, the following are worth noting:

1. The list of Official Mexican Standards issued to determine sampling and analysis parameters that shall be used for the application of the NOM is updated.

2. More detailed classification of federal waterways and focus on subsequent uses, for the purpose of improving management and protection of such collection bodies.

3. Update of the parameters used for measuring water quality of collection bodies, through the incorporation of parameters known as Chemical Oxygen Demand (“COD”), toxicity and color index, and Total Organic Carbon (“TOC”) in substitution of the COD, specifically as to the organic contamination index with a concentration higher than 1000 mg/L chlorides.

4. The allowable limit for contaminants of wastewater discharges is modified for each waterway where such wastewater is disposed of, divided into: i) rivers, streams, canals, drains; ii) reservoirs, lakes and lakes; iii) Mexican marine waters; and iv) ground, classified in green area watering, filtration and other types of watering, and karstic. Therefore, this NOM does not apply to waste water discharged exclusively from rain sewage, or directly from Municipal wastewater sewer systems.

5. A Spanish version of tables 1 and 2 of the Regulatory Schedule of the NOM may be reviewed here.

6. Evaluation procedures for NOM compliance per requests of interested parties is updated, for both private and official purposes.

The NOM will enter into force 365 calendar days as of the publication in the Official Journal of the Federation, meaning on March 11, 2023, except for:

a. Allowable parameters and limits set forth in tables 1 and 2 of the NOM, and the Regulation Schedule, which will enter into force on April 3, 2023; therefore, until such enter into force, wastewater discharges will remain regulated by sections 4.1, 4.2, 4.3, tables 2 and 3 of NOM-001-SEMARNAT-1996.

b. Allowable parameters and limits on true color and acute toxicity as provided in table 1 will enter into force on the fourth anniversary of publication of the NOM in the Official Journal of the Federation.

If your company has a wastewater permit to discharge into Federal waterways, it is very important to review the updated discharge parameters, evaluate the operative and economic implications, and also be prepared to comply with the NOM in a timely manner.

CCN México Report™

MAY - JUNE 2022

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