Cafes, restaurants, pubs and shops are being urged to open up their toilets for general public use under an initiative to tackle the growing national shortage of free conveniences.

Over the past two decades the number of public toilets in the UK has slumped by more than a third (39%), according to responses to freedom of information requests, as local councils’ increasingly squeezed budgets lead to mass closures.

The total has fallen from 3,955 in 2000 to 2,414 this year, according to data submitted to the British Toilet Association (BTA) by 266 councils in England, Wales, Scotland and Northern Ireland.

In England alone, the average council runs only 15 public toilets, with each having to serve an average of more than 12,500 people.

The BTA’s new “Use Our Loos” campaign is urging businesses to make their toilets available to non-customers.

“We know councils are under immense pressure with their budgets and despite having no legal obligation to maintain these public facilities they have continued to try to halt the rapid rate of decline,” said Raymond Martin, director of the BTA. “Use our Loos is a community-oriented solution not about opening more public toilets but making more toilets public that already exist.”

Each participating outlet will be encouraged to have a sticker on display so the public can easily spot a business happy for people to use its toilets without necessarily being a customer. The scheme is similar to a model encouraging businesses to offer free water refills to non-customers. The Refill campaign aims to break the stigma around asking for water for free even if customers have not purchased anything else.

Some areas – including Bolsover, Milton Keynes, Redditch and Wakefield – are without a single free public toilet. The BTA said this could be a challenge for many, particularly older people, families with small children and people with medical conditions.

A spokesperson for the Local Government Association said: “Councils are doing everything they can to keep public toilets open and ensure there is provision for people with particular needs. With substantial reductions to their budgets, councils have had to make tough choices about public facilities but are finding innovative ways of tackling this issue.”