The organisation of sewers and systems is closely related to the different types of industry and, as a result, a whole array of configurations exist. In all cases, it is essential to avoid unnecessary dilution during treatment. The following principles must be carefully followed: - cooling water, if not treated in an open recirculating system, and non-polluted rain water are discarded in separate systems, - waste process waters presenting high toxic concentrations or specific pollutants are collected separately, as for example, cyanide water, chromate water, saline water, - potentially polluted rain water is conveyed to the treatment plant, - water.
