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Santa Monica Reduces Potable Water Usage with Library Rooftop Rainwater Capture System

Santa Monica, CA, USA

At a Glance

The City of Santa Monica built the Pico Branch Library with a focus on reducing potable water usage to meet its goal of water self-sufficiency. 80% of the facility’s water needed for urinal and toilet flushing can be met with non-potable water collected by the facility’s rooftop rainwater harvesting system.

Problem Addressed

Located in Southern California and plagued by water shortages due to drought, the city of Santa Monica set a goal of achieving water self-sufficiency to avoid the high costs of importing water as well as meet the future water demands of residents. First put forward in 2011, the goal of achieving water self-sufficiency became the impetus for the development of new projects to reduce reliance on outside sources through the capture and reuse of local water.

Santa Monica used/is using a rooftop rainwater capture system to address this/these challenge(s).

Solution(s) Used

The Santa Monica Pico Branch Library, completed in 2014, is Santa Monica’s first municipal building to harvest rainwater for indoor use and to achieve the coveted U.S. Green Building Council’s LEED™ Platinum status for innovative design.

The project harvests rooftop rainwater for direct onsite indoor use in flushing toilets and urinals, taking the place of potable water. Under this system, 8,300 gallons can be harvested from the building roofs after a one-inch rain event. Taking average yearly rainfall into account, 100,000 gallons can be expected to be harvested from the facility’s rooftops annually. This volume of water equates to 80% of the expected annual demand from toilet and urinal flushing in the facility. Another equally significant benefit of the project is the reduction in stormwater that often draws pollution to waterways. By capturing rainwater at the rooftop before it hits the ground, the project is actively reducing the negative impacts of stormwater.

Further innovation included the use of drought-tolerant or native plants to reduce potable water use by 59%, as well as high-efficiency plumbing fixtures to reduce indoor potable water use by 69%.

Energy-efficiency measures that contributed to the LEED Platinum certification include the building being powered by 100% renewable energy through photovoltaic cells mounted on trellises.

Outcomes

  1. The rooftop water harvesting system can harvest 8,300 gallons after a one-inch rain event, with an expected annual capture of 100,000 gallons
  2. Yearly rainwater capture can meet 80% of the facility’s demand for water from toilet and urinal flushing
  3. Use of drought-tolerant or native plants reduced potable water use by 59%, and high-efficiency plumbing fixtures reduced indoor potable water use by 69%
  4. By investing in water self-sufficiency, The City of Santa Monica will be better prepared to handle the effects of climate change on its water supply
  5. Through the capture of rainwater at the rooftop, the city is minimizing the negative impacts of stormwater and the pollution it often carries into waterways

Something Unique

The Pico Branch Library is the first municipal building in Santa Monica to harvest rainwater for indoor use

The Pico Branch Library was certified LEED™ Platinum status for its innovative design.

Who Should Consider?

Towns, cities, or counties looking to reduce reliance on potable water usage by increasing the reuse and capture of rain and stormwater.

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