Water conservation and circular water reuse in clinical haemodialysis facilities: a scoping review.

INTRODUCTION: Haemodialysis is a life-sustaining but resource-intensive therapy with a substantial water footprint, estimated globally at 270 billion litres annually and approximately 78,000 L per patient. Green dialysis strategies increasingly focus on reducing dialysate-related water demand and recovering reverse osmosis RW; however, evidence remains dispersed across clinical studies, service reports and feasibility analyses. This scoping review mapped and synthesised literature on water conservation and reuse strategies in haemodialysis. METHODS: A scoping review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered with the Open Science Framework. PubMed, EMBASE, Web of Science, Scopus and CINAHL were systematically searched. Extracted data included study design, setting, participants or dialysis service characteristics, water use measures, reported water savings, safety, and environmental or operational outcomes. RESULTS: 14 studies were included: nine dialysate flow modification studies and five RW reuse studies. Reported water savings ranged from 24 L/haemodialysis session to 162.3 L/treatment. Reducing dialysate flow from 500 to 300 mL/min saved approximately 48 L/session without major short-term compromise in dialysis adequacy. Reusable volumes ranged from >250 L/session to 1.1 million m3/year nationally. Facility-level reuse ranged from approximately 1.2-4.5 million L/year per centre, with applications including sanitation, autoclave steam generation, horticulture, aquaponics and agricultural irrigation. CONCLUSION: Water conservation in haemodialysis appears feasible through reduced dialysate flow and reject water reuse, although the magnitude of gross mains water savings depends on reverse osmosis system efficiency and local infrastructure. Evidence is primarily single centre and heterogeneous; further standardised reporting and long-term clinical, operational, environmental and implementation studies are needed.