In connection to the informative note we published last June 8, 2021[1], we inform you that the Ministry of Environment and Natural Resources («SEMARNAT») announced that the National Consultative Committee for Standardization of Environment and Natural Resources («COMARNAT») approved on Friday, August 27, 2021, 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, and will be published in the Official Gazette of the Federation in the next few days.

Official Mexican Norm NOM-001-SEMARNAT-2021 replaces NOM-001-SEMARNAT-1996, which had not been updated for 25 years and according to SEMARNAT authorities, the parameters established therein had proven to be insufficient to control pollution in water bodies. The main changes contained in the aforementioned Mexican official standard, which will become effective upon publication, are as follows:

  • Section 2 «Normative References» would be modified, to update the list of Mexican Standards for sampling and analysis of the parameters used as reference for the application of the NOM-001-SEMARNAT-2021, eliminating those that have been cancelled or modified.
  • The maximum permissible limits of pollutants in wastewater discharges to receiving bodies of national property will be modified. With this modification, in general, the limits will be stricter.
  • New parameters are incorporated and regulated: chemical oxygen demand (COD), toxicity and true color.
  • The maximum temperature for discharges into rivers is set at 35 degrees Celsius, lowering the parameter that existed in the 1996 NOM by five degrees.
  • The «Total Organic Carbon» parameter will be incorporated to measure the organic pollutant load in waters with a concentration of more than 1000 mg/l of chlorides.
  • The fecal coliform parameter would be replaced by the determination of Escherichia coli.
  • The way in which wastewater discharges are classified will be modified, eliminating the use of the water to be discharged (i.e. agricultural irrigation, urban public, etc.), focusing on the nature of the receiving body (i.e. rivers, streams, canals and drains; reservoirs, lakes and lagoons; Mexican marine zones and estuaries; and soils).

It is important to note that once published in the Official Gazette of the Federation it will be mandatory for those responsible for wastewater discharges into any type of receiving body owned by the Nation.

However, it will not be applicable to water discharges from drains intended exclusively for storm water or to discharges that are discharged directly into municipal drainage and sewage systems.