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From waste to resource: water recycling project to save 30 M gallons per year in San Francisco

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  • From waste to resource: water recycling project to save 30 M gallons per year in San Francisco

For years, groundwater infiltrating beneath the San Francisco Rapid Transit Station located in Powell Street used to be a flooding risk and had to be pumped into the sewer network. Now one of the largest water users in San Francisco, Clearway Energy, is using it as a resource to help the company reduce its water bill, reports the San Francisco Chronicle.

The energy company operates the Energy Center San Francisco, that supplies steam heating services to approximately 180 buildings in the downtown area. For that, they vaporize large amounts of drinking water and send the steam through pipes, to be used for space heating, domestic hot water, air conditioning and industrial processes. The company used to pay a water bill of up to $2.2 million, according to general manager Gordon Judd. That was before they realised that the groundwater draining under the rapid transit station was a potential resource, if they could clean it.

The San Francisco Public Utilities Commission (SFPUC) supported the project with a $500,000 grant, which the company used to install a pipeline and substitute old sump pumps, to transport the groundwater to a plant in Jessie Street. A $3 million investment was also needed for a water treatment facility. It is designed to remove minerals and large debris from the brackish water. According to Judd, water is treated to make it cleaner that drinking water and it is afterwards boiled to generate steam.

Project operations started earlier this year, and it is expected to result in savings of about 30 million gallons of drinking water per year, an amount that could supply 2,000 citizens with water for a whole year. The SFPUC supports this and other initiatives to encourage water conservation, especially water recycling projects where the water source is close to the point of use.

In the future, climate change will lead to more extreme weather, both heavy rains that will put pressure on sewer networks and droughts that will require water conservation. Mayor London Breed applauded the pioneering project and emphasised the city’s commitment to sustainability and protecting water resources: ‘In San Francisco, and throughout California, we need to continue to prepare for the effects of climate change by being more resourceful when it comes to our water supply’.

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