Glastonbury is discouraging its hundreds of thousands of revellers from using plastic bottles to cut down on waste.
The music and arts extravaganza at Worthy Farm in Somerset is following in the footsteps of the smaller Shambala festival which banned plastic bottles last year.
Glasto organisers say festivalgoers can bring their own reusable, BPA-free water bottles and fill them up for free at any of the 400 drinking water taps.
BPA is a chemical in some plastics which has been linked to some health problems.
Charity Water Aid is also selling not-for-profit stainless steel bottles from several water kiosks at Glastonbury. Other green efforts such as low carbon travelling and recycling are encouraged.
Headliners this weekend include Metallica, Arcade Fire, Bryan Ferry and Fatboy Slim.