Analysis of the Structure of Water Demand with the Example of Selected Buildings^†

Round 1

Reviewer 1 Report

1. Reynolds number

   This paper denotes the flow rate and the pipe size at the same time (e.g., 2.5 m^3/h, DN20). Since two pipe diameters (15 mm, 20 mm) are discussed, it would be better if the authors discuss in terms of Reynolds number. It is because the flow meter performance depends on the Reynolds number.

2. Peak factors

   The authors explain the meaning of peak factors in Table 4. However, there are no clear definitions (mathematical expressions) in this paper. Therefore, the reviewer could not understand why high peak factors indicate the efficient water distribution.

3. Reference

   Even though the authors mention the Polish standard (abolished) and MID several times, international versions of related standards must be mentioned. The reviewer could not follow the references written in Polish.

   Some researches such as D. Schumann et al. (2016) might be helpful to consider technological issue related with water meters. (file attached)

4. Minor comments

- Table 2, 1.8 / 2.4 m^3/h should be (1.8 – 2.4) m^3/h.

- Line 208, 124 dm^3/inhabitant*day should be 124 dm^3/(inhabitant*day).

- Line 209, 80 / 100 dm^3/inhabitant*day should be (80 – 100) dm^3/(inhabitant *day).

- Line 245, 0,45 / 0,6 Q_3 should be (0.45 – 0.6) Q_3.

- It would be better if automatic watering systems are explained.

Comments for author File: Comments.pdf

Author Response

Dear Sir/Madam

In response to the review, I would like to thank you for your time and valuable comments. I tried to consider all the comments when correcting the article.

Point 1. Reynolds number

This paper denotes the flow rate and the pipe size at the same time (e.g., 2.5 m^3/h, DN20). Since two pipe diameters (15 mm, 20 mm) are discussed, it would be better if the authors discuss in terms of Reynolds number. It is because the flow meter performance depends on the Reynolds number.

Response 1. The purpose of the article was to present the variability of water demand for single-family houses. On the basis of measured values of flows, the coefficients of irregularity were determined by installed water meters and it was checked whether they are the optimal devices for given operating conditions. It was not the purpose of the article to compare the work of individual water meters, which should be carried out for the same value of the Reynolds number. The selection of water meters was performed based on the device parameters specified by the manufacturers. The water meter works most often for a large range of water flow variability, eg. the iPerl DN 15 meter has a start-up threshold of 3,13 l/h, and the overload flow rate is 3125 l/h. The purpose of the article was not to determine the parameters of water meters, where the value of the Reynolds number would be important but the optimal choice of the device from the ones available on the market.

Point 2. Peak factors

The authors explain the meaning of peak factors in Table 4. However, there are no clear definitions (mathematical expressions) in this paper. Therefore, the reviewer could not understand why high peak factors indicate the efficient water distribution.

Response 2. Peak factors determine the forecasted or observed variability of water flow in the daily cycle - Nd or hourly - Nh. The article supplements the formulas on the basis of which both factors are calculated. Correct determination of the factors, and at the same time the variability of water flows, enables optimal selection of the water meter. The correct selection of a water meter is when the measuring range includes both the minimum flows observed for a given building as well as the maximum, and the error is below the permissible maximum.

Point 3. Reference

Even though the authors mention the Polish standard (abolished) and MID several times, international versions of related standards must be mentioned. The reviewer could not follow the references written in Polish.

Respons 4. The article is mainly based on the MID Directive, due to the fact that it is a legal act in force in the area of the European Union. The "Introduction" chapter has been supplemented with the standards developed by the International Organization of Legal Metrology (OIML) and in force e.g. in Australia.

Point 4. All the amendments have been included in the text and automatic irrigation systems have been described.

The manuscript was checked by a native speaker.

Yours faithfully

Urszula Kepa

Reviewer 2 Report

Dear authors,

This work aims to propose water meter dimensioning for single family houses in Poland. The study follows the guidelines of the Measuring Instruments Directive 2014/32/EU. 

My general comments regarding your manuscript are as follows:

Your abstract needs rewriting in order to be a good and interesting summary of your work. 

You should include in your introduction a paragraph regarding the state-of-the-art of water meters and sensors including smart meters. I guess that you aim to include your findings in future Polish legislation. So it would be appropriate to link your findings with other relevant research work. Some (not exhaustive) suggestions could be:

Fontanazza, C. M., Freni, G., La Loggia, G., Notaro, V., & Puleo, V. (2012). A composite indicator for water meter replacement in an urban distribution network. Urban Water Journal, 9(6), 419-428.

Mutikanga, H. E. (2014). Residential water meter selection using the analytical hierarchy process. Journal‐American Water Works Association, 106(5), E233-E241.

Yazdandoost, F., & Izadi, A. (2018). An asset management approach to optimize water meter replacement. Environmental Modelling & Software, 104, 270-281.

Moahloli, A., Marnewick, A., & Pretorius, J. H. C. (2019). Domestic water meter optimal replacement period to minimize water revenue loss. Water SA, 45(2), 165-173. 

The overall conclusion is that flow meters with diameter of DN 15mm can be installed instead of DN 20mm. Is this the only result of your study?

Author Response

Dear Sir/Madam

In response to the review, I would like to thank you for your time and valuable comments. I tried to consider all the comments when correcting the article.

The abstract has been corrected to cover all the main aspects of the article.

The paragraph about the state-of-the-art of water meters was added. The suggested literature have been taken into account as well as other, additional research due to the difficulty in tracking down all the prompted articles.

The main purpose of the article was to determine the actual values of water demand and variability of flows for single-family houses. These values were compared with those defined in the literature (which are the basis for dimensioning of water supply system and appliances).

The manuscript was checked by a native speaker.

Yours faithfully

Urszula Kepa

Round 2

Reviewer 1 Report

There are no further comments since the authors responded to all the questions raised by the reviewer.