Water Network Loss Control System ^†

Abstract

This study addresses the issue of water losses in drinking water distribution networks, a problem exacerbated by climate change, drought, and aging infrastructure. The research was conducted in the operational area of Frýdek-Místek, managed by Severomoravské vodovody a kanalizace Ostrava a.s., covering 59 municipalities, 1024.4 km of pipeline, and more than 32,594 service connections. The objective was to evaluate the impact of implementing the “Leakage monitor” software system (ver. 19-11-2024), which focuses on continuous monitoring of minimum night flows (Q_min), on the reduction in Non-Revenue Water (NRW). The system, deployed since 2019, enables automated data collection, remote transmission, and analysis for timely leak detection and localization using acoustic and correlator methods within district metered areas. The results confirmed a reduction in NRW from 14.6% in 2019 to 11.5% in 2024. The implementation of a “Leak monitor” has proven to be an effective tool for improving operational efficiency and ensuring both economic and environmental sustainability of water supply systems.

1. Introduction

In recent decades, drought and climate change have significantly affected the availability of water resources across Europe, simultaneously transforming the perspective on water losses in distribution systems from both economic and environmental standpoints [1]. In response to the increasing pressure to manage water more efficiently, the European Union launched a campaign in February 2025 aimed at ensuring sufficient water reserves for the future [2].

One of the key strategies for the protection of water resources involves reducing water losses within distribution networks. Reliable data on water losses are crucial for planning the rehabilitation and modernization of water infrastructure, with the goal of minimizing such losses [3,4].

Numerous studies have reported substantial disparities in water loss levels among member states of the European Union (EU). For instance, a 2021 report [5] indicates that the lowest average share of Non-Revenue Water (NRW) is observed in the Netherlands (~5%), Germany (~6%), and Denmark (~8%). In contrast, other countries report significantly higher values—France (~20%), Belgium (~21%), Poland (~25%), Slovakia (~32%), Italy (~41%), Romania (~42%), and Bulgaria up to 60% [6].

In the Czech Republic, reducing water losses and maintaining low levels has been a long-term priority for water utilities. Due to aging and degraded infrastructure, approximately 15% of drinking water is lost, on average. For comparison, losses in the 1990s reached up to 35% (see Figure 1). The gradual decline in water losses has contributed not only to the stability of water supply but also to the pricing of drinking water [7].

However, water losses differ not only between countries but also between water supply systems within individual EU member states [6]. A report by EurEau (2021) confirms the high variability of NRW percentages, which complicates comprehensive cross-country comparisons of water management efficiency within Europe [9].

To address this challenge, the revised EU Drinking Water Directive (EU 2020/2184) requires member states to report official data on water losses by January 2026. To ensure comparability, a unified methodology is to be used, with the directive recommending the use of the Infrastructure Leakage Index (ILI) or another standardized assessment method [10]. Subsequently, the European Commission is expected to issue a supplementary legal act by 12 January 2028, which will define a threshold value for acceptable water loss levels based on data submitted by member states and an analysis of average loss rates across the EU [10].

Monitoring water distribution systems through regular observation and evaluation of data—particularly flow and pressure—is essential to reducing losses to economically acceptable levels [11,12].

• The Importance of Monitoring

Water network monitoring based on continuous collection and evaluation of flow and pressure data is a fundamental tool for water loss management. Minimizing night flows (Q_min) enables the effective identification of deviations from standard hydraulic behavior, which are statistically associated with leakage. This approach improves leak detection accuracy and shortens the average duration of water losses, thereby directly enhancing both the economic and environmental performance of operations. Moreover, it provides a foundation for long-term infrastructure renewal planning based on quantitative indicators and trend analysis [11,12].

The aim of this study is to analyze the impact of implementing a software-based tool for managing and monitoring water losses on the operational efficiency of the water distribution network operated by Severomoravské vodovody a kanalizace Ostrava a.s. (SmVaK). The research focuses on the Frýdek-Místek water supply system (WSS Frýdek-Místek) during the period 2019–2024. The development of Non-Revenue Water (NRW) volumes was assessed, and the study seeks to quantify the benefits of the implemented leak management system in relation to the long-term optimization of water supply infrastructure operations.

2. Materials and Methods

2.1. Assessment of Water Losses in the Distribution System

One of the fundamental indicators of the operational efficiency of a water distribution network is water loss, defined as the difference between the volume of water entering the system (produced water) and the volume of billed water delivered to end users [13] (Figure 2).

This difference includes both visible failures (e.g., water leaks at the surface) and hidden leaks (e.g., pipe seepage), as well as unregistered withdrawals from the system (e.g., fire department usage or unauthorized connections) and losses due to meter inaccuracies. Water losses are a key indicator of the technical condition of infrastructure and the effectiveness of operational management [8,13].

For quantitative assessment, the water balance structure in accordance with the Czech technical standard ČSN 75 5020:2023 [14] “Reporting of drinking water losses from water supply systems” was used, supplemented by methodological guidelines based on the International water association (IWA) framework [14]. According to this approach, the produced water is considered as 100% of the initial volume for evaluating losses. Transfers between water systems and withdrawals outside the distribution network are excluded from the calculation [7]. The following indicators were applied:

• Non-Revenue Water (NRW)

This expresses the ratio of non-revenue water to the total produced water volume. It is one of the most widely used indicators of water losses [14,15].

$$\mathrm{NRW}\mathrm{volume}=\mathrm{VVR}-\mathrm{VF},\left[{\mathrm{m}}^3\right]$$

(1)

$$\mathrm{N}\mathrm{R}\mathrm{W}={\displaystyle \frac{\mathrm{N}\mathrm{R}\mathrm{W}}{\mathrm{V}\mathrm{V}\mathrm{R}}}·100\left[{\displaystyle \frac{{\mathrm{m}}^3}{{\mathrm{m}}^3}}.\%\right]\left[\%\right]$$

(2)

• NRW (%)—Non-Revenue Water percentage;
• NRW volume (m³)—Volume of Non-Revenue Water;
• VVR—System Input Volume (m³);
• VF—Billed Authorized Consumption (m³)

• Specific NRW Losses (S-NRW)

This indicator expresses the volume of non-revenue water recalculated per year per kilometer of water supply network. It allows for comparison of the operational efficiency of different systems and identification of problematic areas.

S-NRW represents the NRW volume recalculated per 1 km of the standardized pipeline length (converted to DN 150 profile). The recalculated length takes into account pipe diameters (DN) to ensure comparability between differently structured systems [13,14,15].

$$\mathrm{S}-\mathrm{N}\mathrm{R}\mathrm{W}={\displaystyle \frac{\mathrm{N}\mathrm{R}\mathrm{W}}{{\mathrm{L}}_{\mathrm{p}\mathrm{ř}\mathrm{e}\mathrm{p}}}\hspace{1em}\hspace{1em}\hspace{1em}}\left[{\displaystyle \frac{{\mathrm{m}}^3}{\mathrm{k}\mathrm{m}}}.\mathrm{y}\mathrm{e}\mathrm{r}\right]$$

(3)

$${\mathrm{L}}_{\mathrm{p}\mathrm{ř}\mathrm{e}\mathrm{p}}={\mathrm{K}}_{\mathrm{i}}.{\mathrm{L}}_{\mathrm{i}}\hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}\left[\mathrm{k}\mathrm{m}\right]$$

(4)

$${\mathrm{K}}_{\mathrm{i}}={\displaystyle \frac{{\mathrm{D}\mathrm{N}}_{\mathrm{i}}}{{\mathrm{D}\mathrm{N}}_{150}}}$$

(5)

• L_přep—recalculated pipe length [km] to a standardized DN 150 profile;
• L_i—actual length of network with the same DN;
• K_i—conversion coefficient for length adjustment;
• DN—Diameter Nominal.

2.2. Instrumentation and Leak Detection Methods

• Frýdek-Místek Distribution System

The study was conducted in the water distribution system operated by SmVaK in the Frýdek-Místek area. This area was selected due to its extensive infrastructure and complex terrain and network configuration. It serves as a representative example of a medium-sized Czech distribution system suitable for evaluating water losses.

The Frýdek-Místek distribution system serves 59 municipalities. The supply system is a combination of gravity-fed sections, pumping stations, and pressure regulation through valves (Figure 3) [13].

The total length of the water network is approximately 1024.4 km. The infrastructure includes 37 reservoirs with a total capacity of 4493 m³, 45 pumping stations, and more than 32,594 service connections with a total length of 171 km [13].

To effectively detect and reduce water losses, a comprehensive system for monitoring minimum night flows (Q_min) was implemented in the Frýdek-Místek area, based on the “Leak monitor” software tool. Development of the system began in 2018 in cooperation with the Danish company DHI. After successful testing, the system was rolled out in all SmVaK operational areas from 2019, replacing an older system that no longer met rapid leak detection requirements. The system enables automated data collection, transmission, and analysis of flow data in selected network sections to identify anomalies linked to probable leaks [11,12,16].

The basic methodology is based on monitoring minimum flows during night hours, when normal consumption is negligible. Persistently elevated night flows are considered indicative of continuous leakage. Flows are measured at selected points equipped with sensors connected to remote data transmission systems (CODEA spol., s.r.o.—Ostrava, Czech Republic; technology using GSM—Global System for Mobile Communications, GPRS—General Packet Radio Service, and LTE—Long Term Evolution). The data are automatically evaluated, and deviations trigger alerts for field inspections [11,16].

Leak localization is carried out using modern diagnostic devices capable of detecting leaks even in densely built-up areas. The tools used include:

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Magnetic locators for identifying buried valves and covers;

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Ground microphones and acoustic rods (“electronic ears”) for surface-level leak detection;

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Correlators for precise leak localization using sound propagation delay analysis;

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Noise loggers for continuous night-time acoustic measurements.

Localization is guided by software analysis and narrows down the problematic sections quickly.

The entire process operates within district metered areas (DMAs) (Figure 4), which were identified as the most efficient operational model. The network is divided into smaller hydraulically isolated units, enabling high-precision water balance assessment and targeted interventions. Monitoring point selection was based on accessibility, representativeness, and availability of historical operational data [16].

The system logs and regularly evaluates the frequency of leaks, detection times, duration, and development of NRW and S-NRW indicators across different DMAs. These results are used to optimize interventions, support long-term infrastructure planning, and evaluate the economic effectiveness of leak reduction measures [16].

Core functions of the system include:

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Automated data collection and alert generation;

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Timely leak localization in critical areas;

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Use of remote data transmission (GSM, GRS, LTE);

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Detailed leak analysis by area;

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Automated export to Microsoft Excel;

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Economic evaluation of detected leaks;

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Historical data storage in a database;

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Streamlined event tracking and standardized processes [16].

3. Results and Discussion

The implementation of the “Leakage monitor” system by SmVaK in 2019 has significantly improved water loss management, particularly within the WSS Frýdek-Místek. The system utilizes data from Supervisory Control and Data Acquisition system (SCADA) and automated control and regulation systems (ASŘTP) to continuously evaluate night-time flows, enabling the early and efficient identification of potential leaks and their prompt localization using acoustic methods.

Among the most frequently affected pipelines identified by the system are old cast iron and asbestos cement pipes, which are especially prone to mechanical damage and material degradation [17].

A key feature of the system is the continuous monitoring and real-time evaluation of leakage levels across individual pressure zones. Based on predefined sensitivity parameters, the system distinguishes between short-term consumption fluctuations and actual leaks. Confirmed anomalies are logged into a central database and immediately reported to the operator. The system also automatically evaluates key performance indicators (KPIs), such as:

• The share of Non-Revenue Water (NRW);
• The volume of leakage per kilometer of network (S-NRW).

As a result of the system’s deployment, a clear and measurable decrease in NRW was observed in the monitored area (see Figure 5), which includes 59 municipalities, 1024.4 km of water supply network, and 32,594 service connections with a total length of 171 km [13].

Between 2019 and 2024, water losses in the network were reduced from 14.6% to 11.5%, representing a significant improvement in the efficiency of water resource management.

Simultaneously, a network zoning strategy was implemented, enabling efficient and targeted management of pressure zones within the water distribution system. This approach has led not only to a reduction in water losses, but also to their long-term stabilization, thereby confirming the technical effectiveness of the measures adopted. Regular evaluation of pressure zones supports the optimization of operational conditions and enables a rapid response to deviations from standard network behavior.

The economic efficiency of the approach has been demonstrated primarily through savings in produced water volumes, resulting directly from the reduction in leaks. In addition, all interventions are subject to detailed economic evaluation, which allows for cost optimization and strategic decision-making based on measurable benefits.

The results clearly emphasize the importance of continuous monitoring, targeted pressure management, and automated data evaluation in ensuring the technical and financial sustainability of water distribution system operations, particularly in medium-sized urban agglomerations.

4. Conclusions

The findings of this study confirm that a systematic approach to water distribution network monitoring, based on minimum night flow measurements and the deployment of the advanced software tool “Leak monitor”, represents an effective and practically validated method for managing water losses in urban and peri-urban supply systems. The implemented system enables early detection of network anomalies, accurate localization of hidden leaks, and their economic assessment, significantly contributing to the reduction in Non-Revenue Water (NRW) volumes.

The implementation of a district-based operational model for supply zones, along with the expansion of monitoring points and the targeted use of acoustic and correlating leak detection devices, has led to a statistically significant improvement in spatial resolution of water loss identification and a reduction in leak detection time. Experience from the Frýdek-Místek region demonstrates that the transition to sectional (district-level) management delivers not only operational but also strategic benefits—including improved infrastructure renewal planning, pressure regime optimization, and enhanced investment decision-making.

Key success factors include the integration of a modern software platform, reliable field data, and the expertise of operational staff. This integrated approach has not only reduced operational water losses but also contributed to greater overall efficiency and transparency in the management of the distribution network.

Further system development—particularly in the direction of finer network segmentation, expansion of remote data collection, and automation of evaluation algorithms—offers potential for even more accurate leak identification, along with additional economic and environmental benefits.