This paper describes the introduction of olive mill wastewater (OMW) to replace fresh water normally used in clay brick manufacture. OMW is recognised as the major agro-food industry pollutant in the Mediterranean/North African olive-growing region. The research involved adding OMW to laboratory-produced clay bricks following the same making procedure used at a collaborating Tunisian brick factory. The samples containing OMW were found to be comparable in forming/extrusion performance to a control product that used fresh water. If introduced at the factory scale, this innovation would allow a substantial volume of OMW to be recycled, saving on the fresh water currently used in the brick-forming process. During the subsequent brick drying operation, most of the OMW (similar to 98% water) would be released as vapour. Once in the kiln, the remaining solids in the bricks (calorific value 21-23 MJ kg(-1)) would liberate additional heat, reducing the gross energy from fossil fuel currently required during firing. (c) 2006 Society of Chemical Industry.