Water Loss Management in Small Municipalities: The Situation in Tyrol
- Identify a usable performance indicator (PI) for water loss management that is especially suitable for challenges of very small municipalities.
- Present common sources of water loss in small water distribution networks (WDNs).
- Describe influences of state funding and rehabilitation planning on performance of WDNs (e.g., improving water loss management).
- Discuss additional problems faced by operators of small WDNs.
2. Materials and Methods
2.1. Technical Performance Indicators for WDNs
2.2. Overview of Austrian Standards and State Funding Related to WDNs
2.3. Case Study
2.3.1. Network Characteristics
2.3.2. Missing Data
3. Results and Discussion
3.1. Evaluation of Water Loss Performance
3.2. Identification of Water Losses
3.3. Experiences Regarding Rehabilitation
- Rehabilitation: Although one WDN was very old, it has the lowest PI (PIV is 7%). The initial WDN was constructed in the 1930s with first extensions and then renovations in the 1940s and 1950s, respectively. In the last few years, the network operators have put a lot of effort into renewing the system, reducing both average year of construction (now 1999) and water losses.
- Rehabilitation planning using survival curves: Only one of the investigated WDNs documented repair work due to bursts and leaks in a detailed way such that they could be used for estimating expected service life of pipes with the same construction year. Consequently, rehabilitation planning using survival curves does not provide statistically relevant information for network renewal as the data base is too small in small WDNs.
- On-line hydraulic monitoring: One WDN with less than 1000 connected inhabitants had water losses of 3% of the total water demand. To achieve such a low value, the network operator installed an online monitoring system several years ago. By continuously measuring the system inputs, irregularities and anomalies can be detected, and bursts and leaks can be repaired relatively quickly. In contrast, none of the investigated WDNs used pressure sensors for leakage detection as pressure fluctuation are low due to overdesigned pipes (e.g., regulations about fire flow and minimum pipe diameter) and low water extractions (e.g., distributed system with a low number of connected inhabitants).
- Leakage detection campaigns: Two larger WDNs had a PIV between 20 and 30%, corresponding to a PIILI between 2 and 3, although one of them had a very complex network structure with different pressure zones. To obtain these relatively low levels, leakage detection campaigns were carried out every year to detect failures in the WDNs. As reports from the network operators indicate, lower values of water losses were hard to achieve, but could be maintained through annual inspection. Additionally, repairing bursts and leakages, which are detected by applying leakage detection campaigns, can reduce water losses significantly. For example, a WDN with approximately 1500 inhabitants could reduce water losses from 45 to 7% within two months.
3.4. Additional Problems Faced by Network Operators of Small Municipalities
- Private swimming pools: One of the main stresses affecting small WDNs is the high increase of private swimming pools and the filling of them with drinking water in spring and refilling in summer, which increases required drinking water demand considerably. As mentioned above, online monitoring systems are used to monitor system performance, where an increase of system input can indicate leakages in the system. Therefore, it is difficult to distinguish pool fillings from real leakages, though the period for pool filling can be limited to warm weekends in spring and summer.
- Conflict between settlement expansion and source protection areas: In Tyrol, protection zones have been established for many drinking water sources, in which handling of harmful substances and constructions are restricted. Additionally, settlement area is increasing due to constant expansion. Consequently, an increased potential for conflict between protection of drinking water resources and urban use of the landscape has been identified, and this conflict will increase further in future.
- Limits of harmful substances: At this state of legislation, expansive countermeasures are needed to reduce harmful substances in drinking water. Currently, there is a discussion about decreasing the limits of harmful substances, mainly focusing on arsenic, antimony, and uranium. These substances can be of natural origin (e.g., granite and gneiss are sources of uranium and were common in the case study), but human influences, e.g., contaminated sites in the form of former landfills, can also be identified as possible causes. In this context, this ongoing process may help the water utilities.
4. Summary and Conclusions
Conflicts of Interest
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|Connected inhabitants (-)||224||2951||15,747|
|Total network length (km)||7.0||25.6||103.0|
|Number of connections (-)||40.0||642.0||2945.0|
|Average connection length (m)||7.8||16.8||29.0|
|Network pressure (m)||50.0||79.2||110.0|
|Year of construction||1962||1987||2002|
|Complete dataset||0.931||- 1||0.969|
|Available datasets (connections missing)||0.952||1.000 2||0.952|
|Available datasets (demand missing)||0.954||0.998||0.965|
|Estimation missing data (used approach)||0.952||0.998||0.955|
|Failures (-)||Main pipes||0.0||1.6||4.0|
|Water losses (l/s)||Main pipes||0.0||1.2||4.2|
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Oberascher, M.; Möderl, M.; Sitzenfrei, R. Water Loss Management in Small Municipalities: The Situation in Tyrol. Water 2020, 12, 3446. https://doi.org/10.3390/w12123446
Oberascher M, Möderl M, Sitzenfrei R. Water Loss Management in Small Municipalities: The Situation in Tyrol. Water. 2020; 12(12):3446. https://doi.org/10.3390/w12123446Chicago/Turabian Style
Oberascher, Martin, Michael Möderl, and Robert Sitzenfrei. 2020. "Water Loss Management in Small Municipalities: The Situation in Tyrol" Water 12, no. 12: 3446. https://doi.org/10.3390/w12123446