Residents in Stillorgan are challenging plans for a project to replace 150-year-old reservoirs.
The €80m project by Irish Water would see the three reservoirs replaced with a large, covered one.
If the project gets the green light from An Bord Pleanála, the existing reservoirs would be drained, decommissioned and landscaped.
The Times Ireland says locals are worried about potential damage to their properties, as many houses are below the surface of the water in the reservoir.
They also claim they could suffer a lack of privacy, and face increased security risk during construction.
The project is to improve the disinfection of drinking water stored in the Stillorgan Reservoir.
Irish Water says it has already invested €3.4m in a new system to improve disinfection.
The project is planned for completion in 2021.