The family-owned soda firm that still uses returnable glass bottles

In the US alone, 127 billion plastic bottles are purchased every year, according to one estimate.

However, one soft drinks firm in the Midwest is keeping old school tradition alive by continuing to sell its products in returnable glass bottles.

For almost a century, until the 1960s, soda bottles in the US were generally meant to be returned.

Customers had to pay a deposit for the sturdy glass bottles. They then got this money back when they returned them to the shop. And the bottles would be washed and refilled over and over again.

Sadly the adoption of plastic meant that this system was phased out, but one soft drinks producer – family-owned Twig's Beverage – has stuck to it.

Customers in its home county of Shawano County, in Wisconsin, pay a $20 (£15) deposit per case of 24.

They can even go direct to the Twig's factory in the city of Shawano to have the same bottles refilled. Some are vintage ones still going strong after 60 or so years.

"We've been seeing some families come in for years," says Twig's vice-president Ben Hartwig. "Cases get passed down and the next family member gets to bring them in.

"That nostalgic feel is something that long-time customers love; they cherish those cases like gold.

"When you look at the date on the bottom of the 16oz bottles, some were manufactured in the 1960s and 70s. It's really cool to see them still going through our washer today. We'd love to keep the tradition alive as long as we can."

Established in 1951 by Hartwig's grandfather Floyd, Twig's signature product is Sun Drop, a citrus-flavoured soft drink developed in 1940s Missouri.

Today, the brand is owned by US drinks giant Keurig Dr Pepper, but Twig's continues to make it under licence for sale in its Wisconsin territory, and it remains an independent company.

Twig's is the last manufacturer of Sun Drop to use returnable glass bottles as opposed to plastic. And it is one of very few to still use real sugar instead of high fructose corn syrup.

Twig's also makes its own-name range of fruit sodas, from root beer to black cherry, and orange to lime. While the company cannot sell Sun Drop outside of its agreed area, it is now aiming to expand sales of its own soda across the Midwest.

They will be in glass bottles, but for the foreseeable future at least, they won't be returnable. "We are slowly picking up distributors and growing the brand," says Hartwig.

"We hope to get Twig's throughout the entirety of the Midwest and go from there."

Explaining why customers further afield will be asked to recycle the bottles instead of returning them, Hartwig adds: "If the people purchasing them are from a different state, it's very unlikely they'll bring them back."

Now celebrating its 75th anniversary, Twig's story began in a Tokyo hospital bed where Floyd Hartwig was recuperating after being shot in both legs during the Korean War.

"That's where he came up with the idea of starting a soda-bottling business," says Ben Hartwig.

The sector was just beginning to boom amid post-World War Two economic prosperity, coupled with a growing preference among consumers for take-home drinks over soda fountains.

Floyd's son Dan bought Twig's in 1986 to keep it in family hands. Today, it is run by Ben, his wife Annelies, and Ben's brothers Jake and Luke. It employs 20 people, and has annual revenues of around $6.5m (£4.8m).

Twig's is interwoven into the culture of Shawano, a close-knit city of little more than 9,000 people. Sun Drop Dayz – a community fundraiser with live music and activities – has been held on the first weekend of June since 2017.

Visitors can also tour Twig's on-site museum to hear its story first-hand, and watch the handcrafted soda being made.

Regarding the day-to-day running of the business, fluctuating prices of ingredients, particularly of sugar, are a persistent threat.

"We are always looking at ways to avoid increasing our prices such as by working with different sugar manufacturers," Hartwig says. "But a lot of our suppliers we have known for years and they've become friends, so it gets tough.

"There are always hurdles but that's what's nice about Twig's being a family business; we come together, share ideas, and see how we can overcome them."

In a field dominated by big name brands, consumers may be surprised to learn how many family-owned soft drinks firms remain in the US.

"The beverage industry is actually a system of small, independent businesses, some of which have been in the same families for generations," a spokesman for the American Beverage Association tells the BBC. "Many produce brands that have been around for more than 100 years."

Looking forward, Hartwig hopes his own two children will go on to continue the family enterprise.

"Our biggest success is keeping on the traditions we have had over the last 75 years, and seeing them passed down from generation to generation. There have been difficult times, but we have kept going," he says.

"The key to Twig's longevity is our passion for the brand and the community itself. The people who come in week after week, and stayed loyal, are the reason we've been successful."

Hartwig adds: "My grandpa started the business in a small building, and my dad was able to expand and grow it, so it'll be interesting to see where me and my brothers are able to take it next. It should be a fun journey."