The mayor of London, Sadiq Khan, has revealed the locations of the first four drinking fountains to be installed in the capital under a new pilot scheme in an effort to combat single-use plastic.

The first fountain was installed last week in Carnaby Street in the West End, while in the coming weeks two will be set up in Liverpool Street station and another in Flat Iron Square in Southwark.

“We want to make sure that it becomes the norm that people can not use single-use plastic bottles,” said Shirley Rodrigues, deputy mayor for environment and energy.

Last year the Guardian discovered that a million plastic bottles are sold worldwide every minute, a large proportion ending up in landfill or in the oceans. The latest move is part of Khan’s plan to tackle plastic waste in the capital, with a further 16 drinking fountains set to be installed by the end of the year.

“To get a grip on needless plastic waste, we need to provide simple ways of refilling and accessing free water, and water fountains are the much-needed solution,” said Khan.

Quick Guide Plastics and our throwaway society Show Why is plastic being demonised? Since the 1950s, 8.3bn tonnes of plastic has been produced. Plastic is seen as a versatile, indispensable product, but the environmental impact is becoming more stark. Plastic is now so pervasive that recycling systems cannot keep up and the leakage into the environment is such that by 2050 plastic in the ocean will outweigh fish. In 2017 scientists found plastic fibres in tap water, and plastic has been found in the stomachs of sea creatures in the deepest part of the ocean. Most plastic waste ends up in landfill sites or leaks into the natural environment, where it is causing huge damage to eco-systems on land and sea, creating near permanent contamination. According to academics in the United States, by 2015, of all the plastic waste generated since the 1950s, only 9% has been recycled, with 12% incinerated and 79% accumulated in landfill sites or the environment. Why are the supermarkets under fire? Producers of plastic include retailers, drinks companies and supermarkets. Supermarkets create more than half of the plastic waste in the household stream in the UK. But they refuse to reveal how much they put on to the streets and how much they pay towards recycling it. Supermarkets are under pressure to reduce their plastic packaging and campaigners argue they have the power to turn off the tap. Much of the packaging they sell to consumers is not recyclable: plastic film, black plastic trays, sleeves on drinks bottles and some coloured plastic. The Recycling Association and other experts believe supermarkets could do much more to make packaging 100% recyclable and reduce the use of plastic. Who pays to clean up the waste? The taxpayer, overwhelmingly. UK producers and retailers pay among the lowest towards recycling and dealing with their waste in Europe. In other countries, the “polluter” is forced to pay much more. In France, a sliding system of charges means those who put more non- recyclable material on the market pay more. What can shoppers do to help? Supermarkets are under pressure, not least from the prime minister, to create plastic-free aisles. A growing number of zero-waste shops are springing up and consumers are being encouraged to ask for products to be sold without plastic. Sandra Laville Photograph: ermingut/E+

But quite where these fountains will appear is up for grabs: landowners, community groups, boroughs and others have until 24 April to apply for a fountain, with £50,000 from the mayor and £25,000 from the provider of the fountains, MIW, set aside for successful applicants to help fund installation.

“One of the key things is that [the site] is accessible, [and] obviously areas with higher footfall are very helpful,” said Dr Heather Koldewey, who will be involved in judging the bids and is co-director of the#OneLess campaign against single-use plastic, a partner in the scheme.

Koldeway said the 20 pilot fountains will include flow meters so that their use can be monitored, while street surveys will be carried out to explore whether the fountains are changing public behaviour.

The city hall funds are part of a £750,000 pot of money earmarked by the mayor to fund a three-year plan to reduce London’s plastic waste. However, Khan has pledged another £6m for environmental improvements in London that includes installing more water fountains, informed by the results from the pilot.

While drinking fountains were once abundant in the capital, an exclusive Guardian investigation last year found the provision of drinking fountains currently varies dramatically between London boroughs. While Lambeth reported 25, other councils, including Kingston and Sutton, reported having none.

Rodrigues said programmes such as Sir David Attenborough’s Blue Planet II had helped propel the problem of single-use plastic into public consciousness. “What the mayor is saying is we can do something now, we don’t want to wait while [the] government dithers about putting out yet another consultation on what to do. We can see it with our own eyes what is happening in the oceans,” she said.

Koldeway, who is also head of marine and freshwater conservation at the Zoological Society of London, said the impact of plastic was all too apparent on a recent research expedition to the remote Chagos Archipelago in the Indian Ocean.“In just 20 minutes [we] accumulated 334 plastic water bottles from 10 different countries, just through a quick beach clean and count,” she said.

Earlier this month Khan announced the start of a free tap water refill pilot, working with partners including the charity City to Sea, which set up Bristol’s tap water refill scheme.

Paul O’Connell, a trustee of the Drinking Fountain Association that is also working to increase the number of drinking fountains, welcomed Khan’s latest announcement and said he hoped other cities will follow suit. “When you are outside your home and you are thirsty, if there is no drinking fountain, pretty much your only option is to buy plastic bottled water,” he said.