Non-conventional Water Resources for Irrigation: a Critical Scientometric Review of Global Research Trends, Evidence Gaps, and Priorities (2020–2024)

Abstract

Water scarcity has accelerated scientific interest in non-conventional water resources for irrigation. This study combined performance analysis, science mapping, and a critical interpretive synthesis of Web of Science literature published from 2020 to 2024 to evaluate not only the structure of the field, but also the strength, limitations, and practical implications of the available evidence. Publication volume increased from 122 articles in 2020 to 174 in 2024, with a peak of 190 in 2022, and collaboration networks were concentrated in Brazil, China, the Middle East, and Europe. However, bibliometric visibility did not equate to evidence maturity. The literature consistently reports potential benefits, including freshwater substitution, nutrient recovery, and greater resilience to drought, alongside unresolved risks related to salinity and sodicity, contaminants of emerging concern, pathogens, antibiotic-resistance determinants, and groundwater contamination. The critical synthesis identified five major limitations: predominance of short-term and site-specific experiments; inconsistent characterization of water, soil, and crops; scarce long-term, multi-compartment monitoring; fragmented regulatory thresholds; and limited techno-economic and adoption evidence. We therefore propose priorities centered on harmonized reporting, multi-season field trials, mixture-based and One Health risk assessment, fit-for-purpose treatment, validation of digital monitoring under operational conditions, lifecycle assessment, and context-specific regulation. Non-conventional water should not be framed as universally sustainable; its performance is conditional on source quality, treatment, crop sensitivity, soil buffering capacity, irrigation design, monitoring, and governance. The field is scientifically active, but its operational readiness remains uneven. Global research on non-conventional irrigation water expanded from 2020 to 2024. Evidence remains fragmented across water types, crops, soils, and climates. Benefits coexist with salinity, contaminants, pathogens, and soil degradation risks. One Health assessments and multi-season field trials are urgently needed. Harmonized monitoring, treatment, and regulation can support safe water reuse.

The authors' abstract, as published at the source. Water Conservation Science and Engineering, 2026 · DOI ↗