Greywater is the wastewater produced in bathtubs, showers, hand basins, kitchen sinks, dishwashers and laundry machines. Segregation of greywater and blackwater and on site greywater treatment in order to promote its reuse for toilet flushing and/or garden irrigation is an interesting option especially in water deficient areas. The objective of this study was to characterize the different greywater sources in Greek households and to evaluate the performance of alternative physicochemical treatment systems to treat several types of greywater. Based on the results average daily greywater production was equal to 98 L per person per day and accounts for approximately 70–75% of the total household wastewater production (135 L per person per day). Among the different sources, laundry and kitchen sink are the main contributors to the total greywater load of organic carbon, suspended solids and surfactants, whereas dishwasher and bathroom greywater are the main sources of phosphorus and endocrine disrupting chemicals respectively. Depending on sources, greywater accounts for as low as 15% of the total wastewater load of organic carbon (in the case of light greywater sources), to as high as 74% of the total load organic load (in the case of the heavy greywater sources). On the other hand, the nutrients load of greywater is limited. The application of a physical treatment system consisting of coagulation, sedimentation, sand filtration, granular activated carbon filtration and disinfection can provide for a final effluent with high quality characteristics for onsite reuse, especially when treating light greywater.

灰水是浴缸，淋浴器，洗手池，厨房水槽，洗碗机和洗衣机中产生的废水。灰水和黑水的分离以及现场灰水处理以促进其重用于厕所冲洗和/或花园灌溉是一个有趣的选择，尤其是在缺水地区。这项研究的目的是表征希腊家庭中不同的灰水来源，并评估替代物理化学处理系统处理几种类型的灰水的性能。根据结果​​，平均每日灰水产量等于每人每天98升，约占家庭废水总产量（每人每天135升）的70-75％。在不同的来源中，洗衣和厨房水槽是造成有机碳，悬浮固体和表面活性剂总灰水总负荷的主要因素，而洗碗机和浴室的灰水分别是造成磷和破坏内分泌化学物质的主要来源。根据水源的不同，中水占有机废水总负荷的低至15％（在浅水源中），最高占有机负荷的74％（在重水中）来源）。另一方面，灰水的养分负荷是有限的。包括凝结，沉淀，砂滤，颗粒活性炭过滤和消毒在内的物理处理系统的应用可以为最终废水提供高质量的特性，以供现场重复使用，尤其是在处理浅灰水时。