Travellers will need to bring their own refillable glass or aluminum bottles if they want a drink of water at San Francisco International Airport this summer.

Fox News reports that the airport will ban the sale of single-use plastic water bottles on August 20, applying a city ordinance that went into effect on other publicly owned property in 2014. Travellers who don’t carry their own multi-use containers to the airport will be able to purchase them from terminal shops.

The move is part of the airport’s goal of achieving zero net carbon emissions and energy use and eliminating most landfill waste by 2021.

The San Francisco airport already requires vendors to use compostable take-away boxes, condiment packages, and cutlery. One vendor said that while compliance with that directive has been relatively easy, the ban on sales of plastic water bottles in vending machines and in other outlets could be more challenging.

Airport officials expressed hope that vendors will voluntarily comply with the new rules and that enforcement penalties won’t be necessary.