A new skyscraper in San Francisco could save nearly 30,000 gallons of water per day with its integrated sewage recycling system.
Greywater (the water from showers, sinks and washing machines) is much less expensive to clean and reuse because of the lack of contaminants. Blackwater (the waste from toilets, garbage grinders and dishwashers), on the other hand, takes a lot more effort to make reusable. Pelli Clarke Pelli Architects made the assumption that such recycling and cleaning was integral to the sustainability of its design of one of San Francisco’s latest high-rises. Commercial tenants have already started to move into the Salesforce Tower, and construction of the blackwater recycling system is due to be completed by the end of 2018.
The system is being funded by the city’s first blackwater grant from the Public Utilities Commission and will occupy several basement parking spaces on two levels. The system will treat water from across the building, including rooftop runoff and sewage, and then resupply the premises with plant irrigation and clean toilet water. The Salesforce team estimates that this will save more than seven million gallons of fresh water each year, which is a 76 percent reduction in overall use.
Other ways in which vast amounts of wastewater is being put to new use includes turning olive mill wastewater from olive oil production into biofuel and fertilizer and pumping construction site wastewater into a city’s irrigation, cooling and ornamental fountain systems. How could other cities use recycled water to find solutions to their problems?