In addition to the volumetric fee, there is also a fixed annual connection cost. As regards the small settlements, however. The wholesale tariff applied by ONEP includes a national solidarity contribution (surtaxe) of 0.75 dirhams/m , which was established in 1985. It is designed to offset the operating losses incurred by ONEP in small settlements, where the uniform tariff applied generally does not allow recovery of production costs due to the absence of economies of scale.