Greywater: Limitations and perspective

Onsite separation of black water from greywater (GW) and the latter's onsite reuse have gained popularity in the last three decades. The potential benefits of GW reuse are wide, ranging from direct benefits for the user to large-scale benefits for the whole water sector. However, along with its benefits, GW reuse may pose some risks and challenges that must be mitigated for safe reuse. The challenges are generally divided into health risks, mainly from the presence of pathogenic microorganisms, and environmental risks from the presence of various pollutants, such as sodium, pH and surfactants. This short review highlights the potential benefits of GW reuse along with its major associated challenges, and suggests means to sustainably ensure safe GW reuse.