Abstract Background and Aims Green nephrology encompasses all initiatives in kidney care that have a positive impact on the climate and environment. We know that environmental impact of dialysis is particularly high, considering water consumption and disposable waste production during each session. All that suggests a great opportunity where many improvements should be made. To prepare the dialysate 240 liters of water are needed for one four-hour session with a dialysate flow (Qd) set at 500 ml/min. Including additional water needed to rinse and sterilize the system, this gives approximately 500 liters of water used for one hemodialysis. Lower dialysate flow rate is associated with a significant reduction in the amount of water used for the hemodialysis procedure. An increase in Qd from 500 ml/min to 800 ml/min has been recommended to increase dialysis efficiency. It's benefit was not confirmed in in vivo studies which suggested that increasing the dialysate flow rate offers no benefit in terms of delivered Kt/V. Similarly, studies with a Qd of 400 ml/min showed comparable efficiency. If hemodialysis could be performed equally effectively with less dialysate consumption, water could be significantly saved. The aim of this study was to check whether change of dialysate flow from 500 ml/min to 300 ml/min has a significant impact on dialysis adequacy (measured by Kt/V). Method The study was a retrospective analysis. During the COVID19 surge in January 2022 due to administrative issues in a satellite dialysis center the dialysate flow was reduced to 300 ml/min. The center again increased Qd to 500 ml/min in February 2022. We analyzed laboratory data from 3 months before dialysate flow reduction, in the month with reduced Qd to 300 ml/min, and from 3 months thereafter with Qd set at 500 ml/min. Results 26 patients (10 men and 16 women – all dialysis patients from a satellite dialysis center) were enrolled in the study. Two of them died during observation, therefore 24 people were included in final analysis. Their median age was 72 (66-78) years. ANOVA with repeated measures showed lack of differences between three time points in terms of Kt/V (Qd 500 ml/min - 1.285±0.202, Qd 300 ml/min - 1.275±0.192 and Qd 500 ml/min - 1.337±0.199; p=0.093). Change in serum potassium during hemodialysis did not depend on dialysate flow (ΔK Qd 500ml/min - 1.5±0.5 mmol/l, Qd 300 ml//min - 1.7±0.5 mmol/l, Qd 500 ml/min - 1.6±0.4 mmol/l; p=0.197). Serum phosphorus was comparable between three time points (Qd 500 ml/min - 5.99±1.68 mg/l, Qd 300 ml/min - 5.65±1.4mg/l, Qd 500 ml/min - 6.01±1.67 mg/l; p=0.066). Conclusion Reduction in dialysate flow rate to 300 ml/min is safe for the patients and probably does not cause any short-term negative effects. Thus we can achieve the same therapeutic effect saving water consumption. Larger, long-term studies are needed to confirm the efficacy of this approach.