As the San Francisco Board of Supervisors prepares to vote on an ordinance banning plastic straws, hundreds of small-business owners could be impacted by one problem: bubble tea.

You can drink a cocktail without a straw. You can drink a 32-ounce cola without a straw. But ferrying huge tapioca pearls from the bottom of an icy cup of tea to your mouth? Not going to happen with a spoon. As Andrew Chau, co-owner of the San Francisco-based chain Boba Guys, said, “We literally can’t have an operation without straws.”

If the ordinance passes as drafted on July 31, set to take effect in July 2019, local businesses that sell takeaway cups and lids made out of compostable plastic can’t use straws made from the same material. For the hundreds of independent businesses that sell bubble tea, many of them immigrant-owned, finding a supply of the compostable bubble tea straws may be almost impossible.

On May 15, Supervisor Katy Tang, speaking at a press conference at Boba Guys on Fillmore Street, introduced the Plastic and Litter Reduction Ordinance. The ordinance bans plastic straws, stir sticks, toothpicks and those nameless things cafes stick into your coffee cup lid to prevent your latte from splashing onto your shirt collar.

San Francisco is far from the only city to propose a straw ban. Seattle’s took effect on July 1. Alameda, Oakland, Santa Cruz, Davis, Berkeley and San Luis Obispo are all considering or have proposed similar bans. So have the United Kingdom and Taiwan. Large corporations such as Alaska Airlines and Starbucks have already pledged to ban straws.

In San Francisco, city supervisors have found support from the San Francisco Department of the Environment, which oversees the city’s Zero Waste policy. By weight, plastic straws and stirrers may represent a tiny percentage of all the plastic trash going into landfills, said department director Debbie Raphael, but straws are easily picked up by the wind or the water flowing through storm drains. “Their very small nature makes them so detrimental to the environment and so difficult to deal with,” she said.

Boba, or bubble tea — a Taiwanese invention that first appeared in the Bay Area in the mid-1990s — is ubiquitous in San Francisco. According to Yelp, 86 San Francisco businesses in its listings are specifically labeled as dedicated bubble tea shops. Many more places include bubble tea drinks on their menus: The phrase “bubble tea” is mentioned in the reviews for more than 250 local businesses in total.

Andrew Chau and co-founder Bin Chen, who run five Boba Guys shops in San Francisco and another five elsewhere in California and on the East Coast, decided a few months ago to back the San Francisco ordinance, which they say dovetails with their company’s commitment to sustainability.

Since then, the challenges the ordinance will pose for the bubble tea industry have become more apparent. It’s not just that straws are essential for sucking the large tapioca pearls out of bubble tea, it’s that the tools in question are specialty straws — 11 millimeters in diameter, compared with 5 millimeters for normal straws. Tang, who said she brings a metal straw with her when she goes to bubble tea shops, adds that most of the plastic boba straws are wrapped in even more plastic.

Last fall, Boba Guys director of operations Kris Gilmour brought in samples of compostable straws to test, ranging from thick paper straws to hollowed bamboo tubes to metal straws. All represented a big increase in expenses, especially considering that the San Francisco stores give out 2 million straws a year: Whereas plastic straws cost 1 to 3 cents apiece, paper costs 7 to 19 and compostable plastic 7 to 20.

Boba Guys soon found a supplier to make what the company said are the first bubble tea straws made of polylactic acid, or PLA, in the United States. PLA, generally made from corn starch, is the same degradable plastic used in the compostable cups and lids that San Francisco’s composting program accepts.

Chau said that, last month, he called Tang’s office to tell her aide that he found the perfect replacement. His moment of triumph was short-lived, however. “I hate to break it to you,” Chau said the aide replied, “but PLA is out of the ordinance.”

Supervisor Tang confirms that PLA straws will also be banned. (For the record, Seattle’s ordinance allows them.) “PLA is designed to break down in high-heat settings, which is not the oceans,” Department of the Environment director Raphael said. “That straw or lid, if it ends up in the ocean, it’s not breaking down.”

Problem No. 2: San Francisco’s composting facility provides an environment that does degrade PLA, but straws are too small and light for the mechanized sorter to capture them. Because PLA straws look too much like conventional plastic ones, human eyes can’t catch them, either.

Boba Guys staff said they know of three other straw possibilities: jumbo paper straws from Indiana’s Aardvark, which are thick enough to stay intact for a good 30 minutes of sipping; paper straws from Petaluma’s World Centric; and food-grade, seaweed-based plastic from a new company called Loliware, which Tang confirms would be allowed under the new ordinance.

The rub: None of them is currently available.

Given the consumption rates of Boba Guys’ five locations, supplying San Francisco’s dedicated bubble tea shops may require straws on the magnitude of 30 million to 35 million — and that’s not including all the other cafes that serve iced tea with tapioca pearls.

Because of the rush to order paper straws, Aardvark already has a long backlog. Jumbo straws from neither of the other two companies are on the market yet. Loliware CEO Chelsea Briganti said that by the end of 2019, her company will be able to produce straws by the hundreds of millions, some of which will include bubble tea straws.

San Francisco may be offering businesses a year’s grace period, but it may not be enough. Given the national — even global — interest in switching to compostable straws, the bans are likely to outpace supply, at least for the first few years.

The Department of the Environment insists that even after July 1, 2019, it’s committed to working with businesses to secure alternatives rather than issuing fines.

“If there is a moment when this goes into effect when you’re unable to source the straws you need,” Raphael said, “let’s talk about it and see what we can do to help.”

Jonathan Kauffman is a San Francisco Chronicle staff writer. Email: jkauffman@sfchronicle.com Twitter: @jonkauffman