Extending the Holding Time for Agricultural Water Testing EPA Method 1603 for Produce Growers

Round 1

Reviewer 1 Report

This study claims to extend the holding time for water testing method (US EPA 1603).  

This study lacks novelty, as this work has already been conducted. The scope of this study is very limited as no other properties of water were monitored in this study such as pH, turbidity, organic matter which may affect the results. I think the contribution of this work is not recommended to be published in Water Journal.  

Following suggestions may improve the authenticity of the manuscript.

The results of this study are not enough and require additional data to prove the authors claims. Sampling locations must have the map to show the sampling distribution of Iowa State. Other water quality parameters (pH, organic matter, turbidity and more) need to be added. Statistical design needs more refinement. Add more literature to identify research gaps. 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

This is a timely study as the changing climate and warming temperatures induce the spread of pathogens. Screening/testing for agricultural waters needs to be made easier and more accessible to all produce growers to minimize health risks. 

 

The sample size of the study is small and it was done on a localized area, but it is important to get these results out to others, which might encourage labs located in regions with different climates/environments to test "the extended hours of storage." Thus, may be able to push USEPA to update the method and accept the extended storage times, which would benefit us all.

 

The objective is clearly stated, the study is sufficiently described, and the results support the conclusions. Based on the provided results, it is clear that 6 vs. 24 hours holding-time produced statistically similar/same results. Thus, the manuscript supports the USEPA Method 1603 modification to allow longer storage time prior to analysis for E. coli.

 

I suggest one improvement of the paper. It would make the results more robust if reproducibility of the results/tests is included, and perhaps error bars can be placed on the graph, Figure 1, if available. The paper mentions that a subset of 11 samples was sampled multiple times during the study - I assume that this was done to provide some QC, and evaluate the reproducibility of the analysis. How did these replicates compare?  

 

The manuscript is sufficiently written. There are only a few minor grammar/spelling errors that could be corrected by carefully rereading the text.

 

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

I appreciate authors for doing this work:

But still I have trouble to understand the significance and novelty of this study:

There are already a lot of literature's out there which discusses about the same results, how holding time does not much effect or non-significant while measuring the coliform counts. 

Here's an interesting paper back from 2003. They have done extensive sampling and took different time frames starting from 0 - 48.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC201187/pdf/0326.pdf

Line 62: is it 11 or it should be 101 ?

Line 69 - 70 : what is the reason behind changing the temperature profile after 6 hours for those 24 hours samples? 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Accept

Author Response

The authors appreciate the reviewer's suggestions, and further changes are made to the manuscript.