In wastewater agglomerations whose population and economic activities produce wastewater with a gross organic pollution load of more than 120 kg per day, the treatment mentioned in article R. 2224-11 is biological treatment with secondary decantation or treatment with equivalent purifying power.
However, wastewater treated at altitudes of more than 1,500 metres may be subject to less stringent treatment than that prescribed in the first paragraph, provided that it is established that the discharges do not adversely affect the environment.