The discovery of thousands of unreported private swimming pools in France has handed the French tax authorities an unexpected profit.

More than 20,000 hidden pools were identified as a result of an experiment involving artificial intelligence (AI).

According to French media, they have amassed approximately €10 million (£8.5 million).

Pools can result in increased property taxes because they increase the value of a home and are required to be declared under French law.

During a test in October 2021, software developed by Google and the French consultancy firm Capgemini detected pools on aerial photos of nine French districts.

The regions of Alpes-Maritimes, Var, Bouches-du-Rhône, Ardèche, Rhône, Haute-Savoie, Vendée, Maine-et-Loire, and Morbihan participated in the trial; nevertheless, tax officials have stated that it may now be implemented countrywide.

According to the data website Statista, there were over 3,2 million private swimming pools in France in 2020, with sales already soaring before the Covid epidemic.

However, as more people began working from home, pool installations increased.

According to Le Parisien, an average pool measuring 30 square meters (322 square feet) is charged €200 (£170) every year.

The tax authorities claim that the program might potentially be used to identify unregistered home additions, patios, and gazebos, which also affect property taxes.

The deputy director general of public finances, Antoine Magnant, told Le Parisien, “We are primarily targeting housing additions such as verandas.”

“However, we must ensure that the algorithms can distinguish between structures with a large footprint and dog kennels and playhouses,” he added.

The crackdown follows Julien Bayou of France’s Europe-Ecology Greens party’s refusal to rule out a ban on new private pools.

He told BFMTV that France requires a “new relationship with water” and that a ban would be a “last resort.”

“The difficulty is not to prohibit swimming pools; it is to ensure our essential water demands,” he explained.

His remarks come as France confronts its worst-ever drought, which has left more than 100 municipalities without potable water.

In July, France received only 9.7mm (0.38in) of precipitation, making it the driest month since March 1961, according to Meteo-France.

To conserve water, many of the northwestern and southeastern regions of France have forbidden irrigation.