But few will have suspected their loose change would also lead to a row between Rome's secular authorities and the Catholic Church.
The euros 1.5 million (pounds 1.3 m) of coins scooped out of the stunning Baroque fountain each year are destined for the Catholic charity Caritas to help the city's poor and homeless.
However, Mayor of Rome Virginia Raggi now wants the money spent on the city's crumbling infrastructure instead.
City councillors have approved the change, which is due to take effect from April.
The city council's decision to take over the fountain money was first proposed in 2017, but it was suspended.
"We did not foresee this outcome", said Caritas director Father Benoni Ambarus in an interview with Avvenire, the newspaper of the Italian bishops' conference.
The latest decision has evoked mixed reactions, with many also questioning why the church should have exclusive rights over the money.
The Trevi Fountain, commissioned by Pope Clement XII in 1732, is visited by millions of tourists every year.
Ms Raggi took control of Rome in 2016 for the anti-establishment Five Star Movement, which formed a national coalition government previous year.
The Trevi Fountain is the endpoint of an ancient Roman aqueduct that has brought water to Rome for around 400 years.
In October, thousands of protesters gathered outside city hall to denounce Ms Raggi for failing to address problems including uncollected rubbish and potholed roads.
A BBC report said the tradition of throwing coins was made famous by singer Frank Sinatra's song "Three Coins in the Fountain" in a 1954 film of the same name.
According to statistics, the city has received 4,500 requests for compensation from drivers who claim to have suffered injuries on Rome's streets.