A narrative review on the potential reuse of greywater for irrigation in crop production: pros and cons

Abstract Climate change is a global concern due to its significant impact on water resources, leading to increased hydro-climatic extremes such as droughts, floods, and high temperatures. Consequently, the reuse of greywater for irrigation has gained popularity in recent decades, alongside advancements in treatment methods. It serves as an alternative water conservation strategy that can help preserve existing freshwater bodies as shifting rainfall patterns affect water availability. Numerous studies have investigated the effects of greywater irrigation on crop growth, development, and quality. Research findings indicate that greywater irrigation can have both positive and negative impacts on postharvest crop quality, highlighting the need for proper treatment to reduce heavy metal content and microbial loads. Reusing greywater can alleviate the demand for clean water, thereby reducing pressure on clean water resources. Given the increasing scarcity of clean water, this paper aims to examine the impacts and benefits of greywater reuse for both potable water conservation and the agricultural sector. We present a narrative review of research on greywater irrigation and its effects on crop development, productivity, and product quality. Additionally, we assess the legal implications, environmental concerns, and public perceptions associated with greywater use. Some countries have implemented guidelines and policies to ensure the safe reuse of greywater, thereby promoting water recycling and conservation. Furthermore, we explore the feasibility of using locally available, low-cost greywater treatment alternatives and identify existing knowledge gaps, offering recommendations to ensure the safe and effective use of greywater.