Harvesting and saving rainwater

The 21st Century Library and Heritage Plaza is the most environmentally sustainable public building ever to begin construction in Hayward. The new library will be 100% solar powered, and the new plaza will feature a significant rainwater recycling system, an important consideration in drought-prone California.

This image from the November 18, 2014 design presentation shows a schematic view of the proposed rainwater catchment and storage system. (Click to enlarge)

The Heritage Plaza renovation plan includes an innovative underground rainwater catchment and recycling system that will save and recycle 400,000 gallons of rainwater per year. The water will be filtered and treated then used to flush toilets in the new library and irrigate the trees and landscaping in the plaza.

One particularly challenging aspect of rainwater recycling is the need to store a large enough quantity of captured rainwater to offset water consumption needs during the dry summer months.

When this challenge was presented during a community stakeholder meeting in April 2014, a community member suggested that the basement of the old Main Library, being already excavated, could potentially house a large enough water storage system to resolve this problem.

Upon further analysis, this suggestion proved to be not only feasible, but preliminary estimates show it could potentially save up to 400,000 gallons of water each year. Furthermore, it would produce enough additional “points” to achieve LEED Platinum status for the overall project.

After construction of the new library is complete in late 2017, the deteriorating old library building will be torn down to make way for installation of the underground rainwater reservoir followed by the complete restoration of Heritage Plaza.