The bureaucratic quicksand that brought New York City taxpayers a nearly $5 million park bathroom “has to change,” Mayor Bill de Blasio said Thursday.

Responding to reporting by THE CITY that found the average cost of a park restroom had nearly tripled between 2011 and 2019 — from $1.3 million to just under $3.6 million — the mayor said his administration is determined to streamline a complex procurement system that causes delays and inflates costs.

“It has to change. And I think all of us here are not happy with that situation,” de Blasio said at a City Hall news conference.

“It is a fact that procurement rules got more and more complex over the years, and in the name of making sure everything was done properly — but it also added a lot of layers of complexity and delay,” he added.

“A whole lot of work is being done right now to weed a lot of that out … and that’s going to be something we’ll be doing a lot more on in the coming months.”

Current and former Department of Parks & Recreation officials have complained about duplicative contract oversight that shuffles documents among at least five parts of the government — including the Law Department, Mayor’s Office of Contracts and City Comptroller’s office.

And they say those delays lead frustrated contractors to raise their bids on future projects to account for expected headaches.

Last year, the Parks Department completed its most expensive bathroom project: a $4.7 million facility at Ferry Point Park in The Bronx.

The costs were higher than average because the site was in a remote location of Throggs Neck that’s prone to flooding, according to Parks Department officials.

But the project also included items such as a $6,000 bike rack — which cost four times as much as a similar bike rack installed near a restroom nearing completion in Aqueduct Walk in The Bronx.

Meanwhile, a $6 million loo is in the works in a flood-prone park on Staten Island.