Facebook is joining SFO by banning single-use plastic water bottles at all of its new offices worldwide.

The social media giant, one of the Bay Area’s fastest-growing companies, said Wednesday it won’t have plastic water bottles in new employee cafeterias in Burlingame, Fremont, San Francisco or Sunnyvale. Instead, the company will install water-filling stations.

The company’s existing Menlo Park headquarters is also being retrofitted with filling stations, with the goal of cutting local plastic bottle usage in half. New offices in Los Angeles, Chicago and Austin will also ban plastic bottles.

Critics say plastic bottles are harmful to the environment by increasing pollution and consuming fossil fuels during manufacturing and transportation.

Facebook agrees.

“It's really about us thinking about our sustainability goals ... and being a good corporate steward,” said Juan Salazar, Facebook's director of local policy and community engagement. “This is the standard we set for the company going forward.”

The ban appears to be the largest among any private employer. Facebook has nearly 40,000 employees as of June, and Salazar said around half work in the Bay Area.

Facebook’s ban comes a month after SFO banned plastic water bottles, an unprecedented move at a major airport. Flavored water can still be sold in plastic bottles, and regular water can be sold in glass or aluminum containers.

Facebook has vastly outgrown its Menlo Park headquarters and now has a presence in four Bay Area counties.

The company’s newest office totals 1 million square feet in three buildings in Sunnyvale and is holding an opening ceremony on Wednesday. Known as Moffett Towers II, the offices will include 739 conference rooms and workrooms and two cafeterias, with plans to house 5,000 employees by 2021.

Sunnyvale banned city spending on water bottles in 2008. San Francisco passed a similar ordinance in 2014.

“This fits very well, and we're excited that Facebook is following a similar program,” said Connie Verceles, manager of Sunnyvale’s Economic Development Division.

Verceles said she wasn’t aware of other local companies banning plastic water bottles, but has seen employers shifting towards promoting reusable water bottles.

Facebook is on pace to become one of the largest employers in Sunnyvale, which has become a hotbed for tech expansion. Business registry data shows Google with 9,800 workers, Juniper Networks with 5,100 workers and Lockheed Martin with 4,610 workers, Verceles said.

A number of municipalities including Concord and West Tisbury in Massachusetts have banned single-use water bottles, along with the University of Vermont in Burlington.

Roland Li is a Chronicle staff writer. Email: roland.li@sfchronicle.com Twitter: @rolandlisf