Over the last three decades, San Francisco has seen more than 70 structures go up with dual-plumbing systems that separate potable from recycled water. The buildings can be found in SoMa, Mission Bay, Hunters Point, Lake Merced and other neighborhoods—zones colloquially called “Purple Pipe Districts”—and they range from multi-unit dwellings to high-rises that shoot up dozens of stories, including the city’s tallest structure: Salesforce Tower.
But there’s just one problem.
San Francisco never built a recycled water treatment plant for these buildings. Since the city passed the groundbreaking legislation in 1991, it hasn’t come close to building the facilities it needs to realize its big water dreams. A recycled water plant that will open on the west side next year will only serve parks and golf courses.
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San Francisco will open a recycled water plant on the west side of the city next spring, but this $216 million facility will not connect to any buildings but instead irrigate Golden Gate Park, Lincoln Park Golf Course, the Presidio and other landscaping areas.
The latest attempt to build a recycled water facility on the city’s east side, where the buildings with purple pipes are located, fizzled this spring after officials deemed the price tag prohibitive.
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Salesforce Tower is an exceptional building in San Francisco, but not just because of its size and notable shape. Before erecting the nearly 1,000-foot tower, the owners of the building, Boston Properties, joined with Salesforce and city officials to come up with a plan to retrofit a graywater system in an adjacent building while also building out an on-site recycled water system to treat “black” water. Blackwater contains human waste, while graywater usually consists of runoff from sinks, baths, laundromats and kitchens.
Altogether, the on-site system at Salesforce recycles about 7.8 million gallons of water a year, which comes out to the same amount of water 16,000 residents would use in a year, according to the company.
From the article:
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