Ecoparc 4 of the Barcelona metropolitan area uses water during operation. To avoid using fresh water, it has several systems for harvesting, stocking and treating water:
- Rainwater is harvested in roofs and roads and stocked in its own pond.
- Leachates that drain from composting reactors are sprinkled over the decomposing matter to keep the right humidity.
- The rest of leachates and wastewater produced by the facility are also stored after treatment.