The annual clean-up of the Glastonbury festival site is 90% completed with only 500 of the 55,000 tents brought on site by attendees being left behind, according to the organiser, Emily Eavis, who has called 2019 “a massive improvement” on previous years.

The entire clean-up is expected to take four weeks this year, with the warm weather, in which temperatures reached 30C during the festival, making it more straightforward than in 2017, when it took teams six weeks to complete.

On Tuesday, Eavis posted on Instagram that “99.3% of all tents were taken home” based on analysing aerial photographs of the site during and after the event.

She said there was still work to be done in terms of improving the clean-up and ensuring more items were removed from the site after the festival. “Some of the worst offending campsites did still have several dozen tents left behind,” she said. “Plus we still get camping chairs and air mattresses left behind, alongside standard rubbish – so things are by no means perfect yet.”

There is no estimated price for the clean-up in 2019. However, Eavis said it could cost £500,000 more to return the site to its original state in a wet year. “Sunshine is the biggest impact on the clean-up,” she added. “When the weather is good, people also move around and place things in bins, and the whole waste collection operation runs far more smoothly and efficiently.”

The Daily Mail called the site “a squalid mess” that “makes a mockery of [the festival’s] eco-posturing”, claiming there was a “sea of bottles, plastic bags, cans, tissues, wet wipes and paper cups … mile after mile of it”.

“We tend to get some people looking for that negative angle on the Monday,” said Eavis in response, adding that any photographer looking for shots of rubbish would find something. “Those photos are often taken first thing on Monday morning when a lot of people haven’t even started packing up and heading home, so they’re not really a fair reflection of how the site is left after everyone’s left.”

At this year’s festival, there was a plastic-free system in place, meaning no single-use plastic could be bought on site. The final bill for the removal of rubbish from the site was estimated at £780,000 in 2016 and the move to ban plastic was motivated by the desire to be more eco-friendly and save on clean-up costs.

David Attenborough made an appearance on the final day of the festival on the Pyramid stage and praised the event for its no-plastics policy. “Now this great festival has gone plastic-free,” he said, “that is more than a million bottles of water have not been drunk by you in plastic. Thank you! Thank you!”

During the festival, 2,500 people are involved with waste and recycling – with approximately 1,800 working as volunteers picking litter. After Glastonbury closed its gates on Monday, 600 people – who are paid – began the clean-up operation.