WASHINGTON — The vice president wasn’t offered an official residence until 1975 — and Nelson Rockefeller wasn’t interested.

Walter Mondale, the first vice president to live in the home the government provided, lost hot water midway through his first shower.

Despite the humble beginnings of the vice presidential residence, Mondale — and his successors — came to love the Queen Anne-style house on the grounds of the Naval Observatory. Some past residents argue it’s a better place to live than the White House.

The new book "Number One Observatory Circle" tells the story of a home that the public knows little about – including that it’s still technically a temporary location for the nation’s second family.

“Ask almost any American where the vice president lives, and you’re almost sure to get a look of confusion,” writes author Charles Denyer.

When Denyer posed that question to friends and family members, he got a few guesses. The Blair House? The East Wing? The basement of the White House?

Some of the unfamiliarity can be attributed to the fact that the home is secluded, its 12 acre-compound just part of the 72 acres of the U.S. Naval Observatory grounds, perched on a hilltop in a stately neighborhood about 2.5 miles from the White House. Unlike the White House, there are no public tours and only a small portion of the home can be seen from the street.

“If you don’t know about it, it’s not there,” Denyer said in an interview.

And then there’s the fact that the vice president didn’t get an official home until 174 years after presidents first occupied the White House.

Despite being only a heartbeat away from the Oval Office, the No. 2 was often seen as insignificant or irrelevant. Even through most of the 20th Century, vice presidents lived in a range of personal homes that included small apartments, modest estates and suburban tract homes.

But the growing relevance of the job, the increased security concerns, and a sense of embarrassment led to Congress passing a law in 1966 setting aside 10 acres of land on the U.S. Naval Observatory grounds for a future vice presidential home.  But the $75,000 the law authorized to build a house was never spent. Concerned about the appearance of spending the money while the Vietnam War raged on, Vice President Hubert Humphrey asked that the project be indefinitely delayed as “an example of prudent budget practices.”

It would be eight more years before Congress would come up with a new plan. Instead of building a house on the Naval Observatory property, the vice president would —temporarily — take over the home already occupied by the chief of Naval Operations.

The current resident, Admiral Elmo Zumwalt, opposed the move and trash-talked the house to members of Congress. When he was unable to dissuade the congressional committee chaired by Virginia Sen. Harry Byrd, Zumwalt unsuccessfully ran against Byrd in 1976.

“Mondale told me the notion that the chief of naval operations had to give up the home for an elected official, the vice president, was just simply intolerable” to Zumwalt, Denyer said.

Mondale was the first vice president to live in the residence because Rockefeller preferred to stay in his luxurious mansion after the house formally opened as the official vice presidential residence in 1975. Rockefeller used the residence only for social events.

Betty Ford had chosen the silver, linens and china for the home but Gerald Ford became president — and Rockefeller vice president — before the Fords could move in.

Mondale remembers the house, built in 1893, as being “about the way it was left when the Navy left it, so there was nothing fancy in there.” Part of the floor in the basement, where the kitchen is, was still dirt.

Rust-sputtering water came out of the faucet when daughter Eleanor tried to take a bath.  And the hot water conked out in the middle of the vice president’s first shower.

The Mondales, however, said the water issues made them feel right at home because, as Eleanor said in a 1977 interview, “one of the steady visitors to our old house was the plumber.”

There would be many upgrades to the house over the years, and not just to the plumbing. Some of the changes were for security reasons. Others were for general modernization. And accommodations were also made to suit the different needs of the various families living there.

“It really changed from one administration to another,” Denyer said. It could be a very formal museum-like showcase for art, as it was under Joan Mondale’s art advocacy. Or, when Gore’s young family lived there, there might be lacrosse sticks and drumsticks everywhere.

The families also left permanent contributions.

Joan Mondale created on the first floor an official library filled with books and publications by past vice presidents.

George H. W. Bush had a horseshoe pit installed.

Dan Quayle refurbished the putting green and added an exercise room, pool house and swimming pool — the latter earning the gratitude of Joe Biden, whose granddaughters loved to swim.

“No one can say a negative thing about Dan Quayle…he built that pool,” Biden told reporters in 2010. “He’s my favorite vice president.”

Biden’s contribution to the grounds include a love note he attached to one of the tall trees to surprise his wife. The plaque reads: “Joe Loves Jill, Valentine’s Day 2010.”

The Bidens also created a “Family Heritage Garden,” with flagstones representing the vice presidents and their family members — including pets — who have lived there.

The Bidens were succeeded by an especially pet-loving family, Mike and Karen Pence, whose rabbit has its own Instagram account.

Karen Pence installed a honeybee hive on the grounds in June, several months after the Pences became only the seventh set of full-time residents.

Some of the improvements to the residence have been financed through a foundation the Quayles created in 1991.

Still, millions of taxpayer dollars have been spent updating a home that was supposed to be temporary. There’s a marker on the grounds where the permanent vice presidential residence was potentially going to be built, but probably never will.

“As they continue to spend millions on security and maintenance and operational upgrades, I don’t see — nor does anybody I’ve spoken to — a reason why the vice president would ever leave,” Denyer said.

And all have fond memories of their time there, particularly enjoying the relatively-secluded retreat offered from their fishbowl lives.

“It was a true home. It wasn’t some big glass house like the White House,” Denyer said. “I couldn’t find any vice president to say anything remotely critical.”