Big companies are testing a return to the “milkman model”—that is, addressing waste by shifting to reusable containers. Twenty-five of the world’s biggest brands said they will make the change this summer, including Procter & Gamble Co., Nestlé SA, PepsiCo Inc. and Unilever PLC, the Wall Street Journal reported. These companies will use glass, steel, and other reusable containers that can be returned and cleaned to be used again. The participating companies see it as a way to reduce waste—and there’s a lot of it. According to data reported by the Earth Day Network, 9.1 billion tons of plastic has been produced since the 1950s when it was first introduced, and most of it still exists in some form. “From a philosophical point of view, we have got to lean in and learn about this stuff,” Simon Lowden, the marketing head for PepsiCo’s snacks business told the Journal. “People talk about recyclability and reuse and say they’d like to be involved in helping the environment, so let’s see if it’s true.” Business leaders in Davos this week for the World Economic Forum also discussed the issue of plastic waste. A new shopping platform, called Loop announced at the forum on Thursday that it would start delivering products like shampoo and laundry detergent for manufacturers in reusable containers, doing away with the disposable plastic containers, The Associated Press reported. Brands partnering with Loop include Nestle, Procter & Gamble, PepsiCo, and others. “Our goal is that by 2030, all of our packaging will be reusable or recyclable,” Virginie Helias, the vice president, and chief sustainability officer at Procter & Gamble, told the AP. Loop will start its offer with 300 products, with plans to expand down the line. Products include Pantene shampoo, which would be delivered in an aluminum pump container, and Haagen-Dazs Ice Cream, which would come in a stainless steel tub. “We have invented a process whereby we deconstruct PET plastic and polyester fiber into it base ingredients and then repolymerize them back into virgin-quality plastic. A great example would be to take an old used polyester carpet or sweater and turn that into a water bottle for one of our many clients such as Coca Cola or Pepsi-Cola,” Daniel Solomita, Loop founder and CEO, said in a statement to Fortune. While the company could help decrease garbage waste, it would also mean more delivery trucks, according to Tom Szaky, the CEO of the recycling company TerraCycle, which is behind Loop. In 2016, transportation, including cars, trucks, commercial aircraft, and railroads represented 28% of U.S. greenhouse gas emissions, according to the Environmental Protection Agency. Light-duty vehicles accounted for 60% of the total transportation-related emissions, followed by medium- and heavy-duty trucks at 23%.