Glass water bottles, so yesterday. Plastic, so convenient; metal, so hip.

But now, in a back-to-the-future sort of way, glass is making a bit of a comeback. And it is being helped in a small way by an entrepreneur who is developing a reusable glass bottle that is hard to break and will not shatter if broken.

The shift to reusable glass water bottles from plastic and metal, which began taking off a couple of years ago, is becoming big business, retailers said.

“I’d say glass bottles account for 20 percent, 30 percent of water bottle sales on our site now,” said Vincent Cobb, founder of reuseit.com, which sells a variety of reusable products. “More and more people are looking for glass.”

The interest does not stop at water bottles.

Consumer concerns that chemicals used in packaging can leach into the products they eat and drink are driving more and more beverage makers and food producers to use glass containers, said Lynn Bragg, president of the Glass Packaging Institute, an industry association.

“They’re also looking for sustainable products to be ecologically responsible.”

Coca-Cola is expanding the distribution of products — Coca-Cola, Diet Coke, Coke Zero and Sprite — that it sells in eight-ounce glass bottles, and S.C. Johnson now sells a line of reusable Ziploc containers called VersaGlass that can be used in a microwave, a freezer and, without their lids, even in an oven up to 400 degrees.

“It’s part of our overall effort to increase packaging diversity so that people have more choices of packaging and portion size,” said Susan Stribling, a Coca-Cola spokeswoman.

No one expects glass to replace plastic anytime soon. But in a survey of more than 4,000 consumers this year by EcoFocus Worldwide, a research and consulting group, 37 percent said they were extremely or very concerned about the health and safety of plastics used in food and water packaging, compared with 33 percent in 2010. EcoFocus also found that 59 percent of the consumers it surveyed used reusable water bottles always or often, up from 56 percent in 2010.

In a smaller survey of about 2,600 people, 42 percent said they had stopped drinking water from plastic bottles or were drinking it less often. Only 8 percent were using glass.

The biggest consumer concern has been bisphenol A, or BPA, an estrogen-mimicking industrial chemical used in some plastics and in the protective coatings that line the inside of some metallic food and beverage containers. Concerns about the chemical have prompted some metal container companies to stop using it. BPA cannot be removed from plastic.

Advocates point out that is not a problem with glass.

“I’m surprised, quite frankly, but a lot of people these days are really doing their research and have great knowledge about the pros and cons of various types of containers,” said Gary Godbey, manager at Trohv, a home store in Baltimore that was the first to carry a new product — the PURE glass bottle — that addressed the primary drawback of glass, namely that it breaks.

The danger of broken glass has prompted many gyms, yoga studios and other places to ban glass bottles. But Walt Himelstein, a scientist turned entrepreneur who developed the PURE bottle, is hoping to change those policies.

Reusable glass water bottles typically use a plastic sleeve for protection. The sleeves on most models have holes that allow the contents of a bottle to be seen but through which broken glass can escape.

Some beverage companies experimented with glass bottles shrink-wrapped with plastic, but most have given up because consumers were not always able to tell if a bottle was broken.

Himelstein said his bottles were different. They are encased in a see-through coating that he developed. If the bottle cracks, the coating holds it in place.

He worked with glass coatings as an environmental chemist at General Physics Corp. in Maryland, and wondered if he could find something similar that would protect consumers from being cut when a reusable glass bottle broke.

“Hazardous materials were delivered in glass bottles with a material coated on the exterior,” said Himelstein, who lives in the Baltimore area. “If a coating could be developed for containers of hazardous materials, I thought, ‘Why not for glass water bottles?’ ”

Almost two years after he started, he had a product he could market. But if finding someone to make bottles was difficult, getting anyone to sell them was worse. He struck out with hotel chains, major retailers, stores on college campuses, just about every potential major point of distribution.

“I had one or two types of bottles,” Himelstein said. “It was tough to get anyone’s attention.”

He faced the same problem when he tried to find investors to expand his line of merchandise. His luck turned in March at a trade show in Chicago when he met Marc Heinke, president and chief executive of Precidio Design, a Canadian company whose primary business has long been making melamine tableware.

Heinke was in the process of selling off that business to focus solely on what he calls “hydration,” containing and preserving all things liquid, and he was looking for the next new thing.

“Walter has come up with the solution to the single biggest problem with glass, which is that it breaks,” he said.

Himelstein and Heinke are working on plans to expand sales of the PURE bottle, relying on Heinke’s business contacts, which include retailers like Lulu Lemon, and his long experience in marketing. They already have plans for a PURE bottle for lunch boxes, for different types of lids and for new colors and labels.

“Then there’s the promotional market,” Heinke said, hopefully, “corporate logos, sports teams, yoga studio logos.”