Mexico City, March 16th, 2022.
On March 11th, 2022, the Official Mexican Standard NOM-001-SEMARNAT-2021, which establishes the permissible limits of pollutants in wastewater discharges into receiving bodies owned by the nation («NOM-001»), was published in the Official Gazette of the Federation.
NOM-001 is mandatory throughout Mexico for all persons responsible for discharging wastewater into any type of receiving body owned by the Nation (rivers, aquifers, basins, riverbeds, waterways, vessels, marine waters, etc.); therefore, the standard does not apply to discharges from storm drains or to discharges into municipal drainage and sewage systems.
The main changes contained in NOM-001 are as follows:
- Section 2 «Normative References» is modified to update the list of Mexican Standards for sampling and analysis of the parameters used as reference for the application of the standard, eliminating those that have been cancelled or modified.
- Permissible limits are established according to the nature of the receiving body into which it is discharged: rivers, streams, canals and drains; reservoirs, lakes and lagoons; Mexican marine areas; and soil.
- The maximum permissible limits of pollutants in wastewater discharges to receiving bodies of national property are modified. With this modification, in general, the limits will be stricter.
- The following parameters are eliminated: BOD5, Floating Matter, Sediment Solids and Fecal Coliforms.
- New parameters are incorporated and regulated: Chemical Oxygen Demand (COD), Toxicity and Color.
- The use of the Total Organic Carbon parameter is incorporated to measure the organic pollutant load, replacing COD, in waters with concentrations of more than 1000 mg/L of chlorides.
- It establishes 35º c as the maximum temperature of water to be discharged into water bodies under federal jurisdiction.
- It regulates the minimum infrastructure that must be in place to ensure that sampling is adequate, representative and in accordance with best sampling practices.
The provisions of NOM-001 will come into force as follows:
1.-NOM-001 will become effective one year after its publication in the DOF, with the exception of what is stated in paragraphs 2 and 3 below:
2.-The parameters and permissible limits established in tables 1 and 2, as well as the Normative Appendix will come into effect on April 3, 2023.
In the meantime, the parameters indicated in NOM-001-SEMARNAT-1996 (numbers 4.1., 4.2., 4.3. and tables 2 and 3) will continue to be in effect.
3.- The parameters and permissible limits for true color and acute toxicity come into effect on March 11th, 2026.
Our environmental practice group is at your service to clarify any doubts you may have on this subject.
S I N C E R E L Y,
Juan Carlos Serra
Jesús Colunga
Ricardo Evangelista
Carolina Nogal
