Onsite Non-Potable Water Systems

UCSC is taking advanced steps to reduce our consumption of potable water. 

Rainwater Catchment

• In 2015, the Athletics and Recreation Wellness Center Rainwater Reclamation project became the campus’s first prototype rainwater catchment system. Rainwater captured in the roof is piped to a 2,825 gallon storage tank. The rainwater is “purple piped” back into the building’s water closets. At 1.28 gallons per flush, the storage volume will accommodate approximately 2,207 flushes (or more if tank is periodically filled by rain) before the tank runs dry and the water closets are switched back over to the irrigation water supply. The system was monitored by Ecology Action for the first year to model the effectiveness of water conservation. It concluded that the system provided approximately 11% of the building’s water needs (60,000 gallons). The system was also monitored for water quality and found no bacteria which removed the need for any UV treatment. The success of this project was borne from funding provided by several sources including the Campus Sustainability Plan, Carbon Fund, and a CA Water Resources Board Proposition 84 Storm Water Planning and Monitoring Grant Program through Ecology Action. Learn more about how the system works.

• In 2024, the Rachel Carson College Dining rainwater catchment system was installed. The rainwater harvesting cistern volume is 3,750 gallons, sized to capture the full runoff volume from the 85th percentile storm event for the retention tributary area. It is estimated to save 81,000 gallons of potable water an average year, or 8% of indoor non-potable water demand. The system was installed to reuse rainwater and meet stormwater management requirements. It serves seven toilets.

• In 2024, two cisterns at Kresge were installed and can contain a total of 92,000 gallons of rainwater. The north cistern holds 53,000 gallons and the south cistern holds 39,000. The tanks will save approximately 530,000 gallons of potable water a year. This system was designed to capture roof and site runoff for reuse and stormwater management requirements. It serves toilet flushing and site irrigation.

• In 2017, the Arboretum received a Carbon Fund grant for rainwater catchment tanks. In collaboration with the Domes Future Garden art installation, they’re working to install two 5,200 gallon tanks to catch water off of the main office building to water plants within dome-shaped greenhouses. 
• CURRENTLY, THESE TANKS ARE NOT OPPERATING AT THE ARB AND ARE LOOKING FOR A HOME! Contact elvaugha@ucsc.edu with interest.

The Arboretum's two 5,200 gallon rainwater catchment tanks. Courtesy: Martin Quigley 

Purple Pipe

“Purple piping” refers to lines designated for recycled water, which is treated to a level suitable for irrigation, industrial use, flushing toilets, etc., but not for drinking.

• In 2010, Porter College Dining Commons and Housing Seismic Corrections Project 3045 installed a dedicated purple pipe system to the housing bathroom water closets in anticipation that recycled or reclaimed water would become available in the future.  
• Four dorms in upper Crown College have been renovated to have a purple pipe system in place with separate point of contacts and metering for future integration into a recycled water system.

Fleet Wash Station

Fleet Services is the home of the campus' 100% closed loop water recycling wash station. Learn more.

Wastewater Treatment

• The Student Housing West Heller Housing project is designed to have a wastewater treatment facility to feed both water closets and irrigation. These large project should have no new non-potable water consumption!

Research 

UCSC’s Impact Designs Engineering and Sustainability through Student Service (IDEASS) program has helped advance multiple rainwater catchment projects throughout the community:

• They’ve helped Bay View Elementary School implement rain catchment and water conservation. Learn more.  
• In 2010, they installed two 5,000 gallons tanks for the school garden irrigation at Natural Bridges Green Career High School.
• They installed a 1,100 gallon tank for irrigation and future toilet flushing at a west side residence.