One year on: Tethered caps reduce litter and reshape beverage bottle design

A year since the implementation of tethered caps, KHS highlights how design experience is central to bottle top innovation, while Zwerfinator, a Netherlands-based environmental activist group, reports a decrease in the number of caps littered in the environment.

Tethered caps were introduced under the EU’s Single-Use Plastics Directive in July 2024. The directive mandates that single-use beverage containers of up to three liters must have attached lids. It aims to reduce the amount of plastic pollution caused by littering.

Packaging Insights speaks to KHS and Zwerfinator about the law’s impact on the industry, consumers, and environment.

“In the fight against plastic pollution, we must pull out all the stops and try new approaches. A lot of plastic caps used to end up as litter and eventually made their way to the oceans,” says Dirk Groot, founder of Zwerfinator.

“Over time, these caps also break down into microplastics, which enter the food chain and ultimately end up on our plates.” 

Consumer confusion amid design challenges 

Manfred Härtel, filling product manager at KHS, outlines how the additional retaining ring of tethered caps required KHS to create a different design for conveying and handling bottles. 

Dirk Groot has observed less bottle caps in the environment since the implementation of the EU’s Single-Use Plastics Directive.Tethered caps are not standardized across the EU, meaning that the KHS team had to gain experience to ensure the safe processing of the caps, says Härtel. 

Since the legislation, KHS has helped its customers find a suitable neck finish that saves on PET material, says Felix Kösters, packaging development for Bottles & Shapes at KHS. “We take all relevant legislative requirements into account and develop the bottle and preform design accordingly.” 

Härtel adds: “Depending on the manufacturer, there are different designs available on the market for tethered caps. These differences naturally arise from patent protection and the need for workarounds on the market.”

A report by the Verbraucherstimme in der Normung (DIN), a Germany-based standardization agency, concluded that consumers find the number of tethered cap solutions confusing and are unsatisfied with the usability of the solutions on the market. 

Groot adds that he was initially skeptical about the measure, but has become “more positive” about the solution.

“47% fewer caps”

Kösters indicates that KHS is not aware of any reports that show the effect of the tethered caps on the reduction of plastic waste, citing a probable lack of data to show a decisive trend-change. He expects more studies to be published in the next few months.

Groot, on the other hand, finds fewer bottle caps in the environment during litter picking sessions. He acknowledges that this might be because of the Netherlands’ DRS.

“The DRS for plastic bottles was introduced in 2021, which led to an 80% decrease in bottles in litter. As a result, the number of caps found in 2023 had already dropped by 24%,” he says.

“The number of bottles hasn’t decreased further since then, but the number of caps has — I’m now finding 47% fewer caps.”

Untethered to the EU

Since the onset of tethered caps, consumers have debated their effectiveness and usability. According to the DIN report, consumers see little environmental benefit arising from the cap solutions, which subsequently negatively impacts acceptance of the caps. 

Groot adds: “I understand the frustration — they can be annoying. Some manufacturers have designed better versions than others. But people will gradually get used to them. It’s not about recycling; it’s about preventing plastic from polluting nature.” 

KHS’s Innocheck TSI uses AI to detect faulty tethered caps (Image Credit: KHS).Groot also argues that consumers must understand the reasoning behind the measure, which he says has not been well communicated — a point that the DIN report reinforces. 

Yet, despite consumer dissatisfaction with the packaging solutions, Kösters and Härtel indicate that there has been an increase in the adoption of tethered gaps from industry customers outside the EU. 

Härtel adds: “There has been a sharp increase in the number of conversions of existing machines to tethered caps. However, some machines outside the EU (around 15%) are also equipped for tethered caps.”

Tethered caps have changed certain aspects of bottle production. For example, KHS recently equipped its Innocheck TSI closure inspection unit with an AI-based fault detection system to better identify defect tethered caps during production.

Lighter bottles for the future 

Groot likens the adoption of tethered caps to the introduction of speed bumps. “They’re annoying, but we got used to them and know why they’re there.” 

For KHS, the EU’s Packaging and Packaging Waste Regulation illuminated a “clear path” for sustainability measures. 

“Lightweighting has been a stable goal of the industry when it comes to bottle design and will likely increase, especially looking at the heavier neck finishes that will likely be fully replaced in the coming years,” predicts Kösters. 

In addition to developments in tethered cap design, he also sees an increasing pressure to use recycled material in bottles. “We also expect more restrictions on different materials in PET bottles to ensure a high-quality material stream in the recycling process.”

For Groot, a DRS for drink packaging is essential to curbing plastic pollution caused by littering. He also advocates for a detailed assessment of what types of plastics pollute the environment. 

“We need to critically examine which types of plastic litter don’t need to be made of plastic and ban those versions, just like the EU has done with straws and cutlery. In many cases, biodegradable alternatives exist — some are new, and some are traditional, like paper bags.”

He concludes: “And of course, awareness and education are always important — but unfortunately, they’re not enough on their own.”