The mathematical technique presented in this paper deals with wastewater minimization within a multiple contaminant environment, where there are multiple storage vessels available for the storage of wastewater. In the multiple storage vessel situation, it is possible to dedicate certain storage vessels to the storage of wastewater with specific contaminants. The mathematical technique is extended to include operations where wastewater produced in one batch is reusable as feed for subsequent batches of the same product. This type of operation enables a plant to operate in an almost zero-effluent fashion. Product integrity is ensured by not allowing different types of wastewater to mix and storing each type of wastewater in a dedicated storage vessel. In both cases, the mathematical model determines the minimum wastewater target and the corresponding production schedule.