It was a pleasure to read and review this well-prepared manuscript by Janik et al.. The objectives, methods, presentation and clarity of writing are first class. The manuscript is well focussed, direct and purposeful and will be a significant contribution to RBF/MAR.  It makes a valuable contribution that will be well recieved by water resources managers, especially as it gives a great deal of design and monitoring information that can be readily adapted to proposed RBF/MAR systems.  I recommend that themanuscript be accepted more or less as s, subject to a few minor editorial suggestions in the attached annotated pdf file. Congratulations on an excellent paper.

The manuscript presents a novel application of EEMMA to RBF in Poland and reveals a strong link between isotopic evidence and catchment processes. The Materials and Methods section is comprehensive and detailed enough, providing clear descriptions of the study site, thorough field and lab methodology, transparent datasets, analytical approaches and clear methodological insights into EEMMA application. The discussion and conclusion provide an international context for the results and offer practical recommendations to RBF operators, justifying high-resolution monitoring.

The primary concerns relate to the language style, with overly long sentences and some redundant phrasing that disrupts the flow. First and foremost, however, the authors should clarify the nomenclature of water drawn from RBF wells. In my opinion, the term 'groundwater abstraction' is not appropriate in the context of water drawn from  the RBF wells. As you correctly pointed out in the Introduction, it is a mixture of surface water and groundwater. I hereby propose changing it just to 'water abstraction' or another term that emphasises that it is a mixture of water from different sources. In addition, it would be beneficial to briefly address the geological structure and hydrogeological conditions in the upstream catchment area, and to include a discussion how these aspects influence the results.

I would express my appreciation for  the comprehensive supplementary data.

Considering the innovative character of the study and its effective presentation I recommend the manuscript for publication with minor corrections. Please refer to the attached PDF file for details.

I would like to congratulate the authors on their hard work and wish them the best of luck with the final publication.