The Ateneo de Manila University encourages the conservation of water in its campuses through the Ateneo Institute of Sustainability and the Central Facilities Management Office. Specific guidelines for this are reflected in the Ateneo Sustainability Policies and Guidelines issued in 2016.
Anchored on these policies, the University has a number of programs in place to encourage conscious water usage. One initiative is the rainwater harvesting facilities used in the Rizal Library and Cervini Cafeteria. Rainwater is collected, treated, and stored for use in flushing toilets. In addition, Rainwater Detention Ponds around the campus collect rainwater to reuse for irrigation and for the maintenance of outdoor spaces. Collecting and using rainwater helps the University consume less municipal water for its operations.
Aside from this, green spaces are irrigated using treated wastewater from nearby buildings. The Decentralized Wastewater Treatment System (DEWATS) and various Building Wastewater Treatment Systems (BWATS) process wastewater using aerobic and anaerobic reactors, ponds, and constructed reed beds that mimic natural systems for wastewater treatment, requiring no inputs of chemicals or electricity. The resulting effluent complies with effluent standards and is used to irrigate nearby green spaces or to clean walkways and driveways on campus.
Other initiatives for water conservation include the use of suitable and less water-dependent plants for landscaping. These initiatives are outlined in the 2020 Ateneo Sustainability Report.