When President Trump hosted Japan’s prime minister at his Mar-a-Lago golf resort in Florida in 2018, he did so lavishly.

Trump welcomed Shinzo Abe to what he called the “Southern White House” with everything from towering flower arrangements to sumptuous dinners, all at eye-popping prices.

U.S. taxpayers footed the bill, the Washington Post reported on Tuesday. And Trump and his companies kept the profits.

“Trump’s club even charged for the smallest of services,” the Post says. “When Trump and Abe met alone, with no food served, the government still got a bill for what they drank.”

What did they drink? Water. At $3 a pop.

The Post says it is reporting this — and much more about Trump’s presidency-for-profit — exclusively and for the first time.

“Since his first month in office, Trump has used his power to direct millions from U.S. taxpayers — and from his political supporters — into his own businesses,” the newspaper says, adding that it tracked the spending “through open records requests and a lawsuit.”

It concludes that Trump has received at least $8.1 million from the government he heads and the campaign fundraising he promotes.

In his nearly four years in office, Trump has visited his own hotels and resorts more than 280 times, the Post says. That’s close to six times every month.

And where the president goes, so go dozens of others — from foreign heads of state to White House flunkies — all of whom could be accommodated at far less expense by using the White House or other government properties in Washington and elsewhere.

Trump’s visits to his properties turned the government into a “captive customer,” the Post says: “What the government needed … it had to buy from Trump’s company.”

So the more he went, the more he got.

Trump’s company charged taxpayers for “hotel rooms, ballrooms, cottages, rental houses, golf carts, votive candles, floating candles, candelabras, furniture moving, resort fees, decorative palm trees, strip steak, chocolate cake, breakfast buffets, $88 bottles of wine and $1,000 worth of liquor for White House aides. And water.”

But there’s more.

“Trump’s campaign and fundraising committee paid $5.6 million to his companies since his inauguration in January 2017. Those payments — turning campaign donations into private revenue — continued even this year, as Trump fell behind in polls and his campaign ran short of money,” the Post says.

Trump’s travels also delivered a particularly big captive customer: the Secret Service.

“When Trump visited Mar-a-Lago for two weeks at Christmas last year, for example, the club charged the Secret Service $32,400 for guest rooms,” the Post says.

Trump’s adult children have brought their father’s company another $260,000 in taxpayer revenue, records show, by taking solo trips to Trump properties with their own Secret Service agents in tow.

“The Trump Organization is not prohibited from accepting the payments,” the Post says. “But the payments did break a key [campaign] promise from 2016: Trump’s pledge that he would ‘completely isolate’ himself from his business once in office, and put his voters’ interests above his own.”

“If I win, I may never see my property,” Trump said then. “Because I’m going to be working for you, I’m not going to have time to go play golf. Believe me.”