Municipality: Ilirska Bistrica, Southwestern Slovenia
Settlements: 64
Population: 13, 362
Altitude: 415m
Koritnice © Municipality of Ilirska Bistrica
Located in Southwestern Slovenia, Ilirska Bistrica is the second-largest municipality in the country by area, covering around 480 km². Out of its 64 settlements, the largest is Ilirska Bistrica (4,350 inhabitants), which serves as the administrative, economic, educational, cultural and social centre of the municipality. Despite its size, the municipality is sparsely populated. This scattered settlement pattern, combined with mountainous and karst* terrain, makes the provision of reliable public services, particularly drinking water supply, especially challenging.
Water supply challenges in Ilirska Bistrica
All water supply systems in Ilirska Bistrica rely on karst water sources, where the quality of raw water is closely linked to weather conditions. Periods of heavy rainfall or drought can therefore directly affect both water availability and quality. Moreover, in addition to supplying villages within the municipality, the main water supply system also serves settlements in neighbouring municipalities and across the border in Croatia, increasing pressure on already vulnerable resources.
Drinking water is treated at the Ilirska Bistrica water treatment facility through ultrafiltration and gas disinfection, processes that remove impurities and ensure safe drinking water for residents. The facility was fully renovated in 2023, significantly improving treatment standards. However, much of the wider distribution network remains old and extensive, covering large elevation differences and relying on numerous pumping stations. This leads to high energy consumption and substantial water losses.
The municipality regularly invests in the most critical sections of the system and actively detects and repairs leaks. Faults caused by ageing materials are addressed through targeted repairs, yet structural challenges persist due to the scale and age of the network.
Ilirska Bistrica as part of the WATERVILL project
As a partner in the WATERVILL project, Ilirska Bistrica brings strong experience in managing local water supply systems. Ensuring good water quality, a reliable supply of drinking water and addressing climate change impacts on rural and mountain water sources, are among the municipality’s priorities.
Ilirska Bistrica is involved in implementing project activities on its territory, serving as one of the pilots and raising awareness in the local community about responsible water use.
A key focus of the WATERVILL pilot in Ilirska Bistrica is the small mountain village of Fabci, home to just 13 residents. Despite ongoing efforts, ensuring a safe and reliable drinking water supply for this settlement remains a challenge. The current reservoir-based solution does not fully meet drinking water standards, posing risks for residents and highlighting the need for a more sustainable approach.
Renovation of the Ilirska Bistrica water treatment plant
What the project will bring locally
Through WATERVILL, the municipality will test innovative solutions, particularly to improve local water supply, ensuring safe and sufficient water for both human consumption and agricultural use, by upgrading infrastructure and optimising water distribution. WATERVILL innovative solutions will help reduce reliance on temporary or inefficient systems and ensure that residents have access to quality drinking water within the public water supply framework.
Beyond its local impact, the pilot in Ilirska Bistrica will address challenges common to many rural and mountainous areas across the Euro-Mediterranean region, such as ageing infrastructure, water scarcity and climate-related risks.
By combining local know-how with smart and nature-based approaches, Ilirska Bistrica’s involvement in WATERVILL contributes to strengthening water resilience, improving public service delivery and supporting sustainable development in climate-vulnerable rural and mountain territories.
PHOTO GALLERY
Illustrations of past water-related investments in the municipality
© Municipality of Ilirska Bistrica
*Karst is a landscape where water flows mainly underground through cracks in limestone rock, making water resources highly sensitive to weather and pollution.
