OpenAI CEO Sam Altman has joined the list of billionaires with expensive property headaches, after the infinity pool of his San Francisco home flooded the lower levels of the property.

In a lawsuit filed to the Superior Court of San Francisco, lawyers allege 950 Lombard Street has “been plagued by shoddy construction, corner cutting, and development efforts to save money, all which lead to pervasive defects in the building.”

Issues have reportedly included raw sewage pouring into hard-to-access areas of the property, with materials bags shoved into pipes “apparently by a disgruntled, unpaid subcontractor.”

Elsewhere, water has been pouring into the property via skylights which were not correctly installed, and leaking pumps throughout the garden’s irrigation system and fountain.

While these issues “frustrated” the owner, the affair came to a head when chlorinated water “filled the entire subfloor of the lower level [of the home]” and then poured down through the roof of the at-home gym, according to the complaint.

Investigations following the flood concluded the water had seeped out of the home’s 40-foot infinity pool, which overlooks the San Francisco Bay and city skyline.

The lawsuit, filed by Dillon Jackson and Brian Schnarr of Hanson Bridgett on behalf of the property owner, 950 Lombard LLC, notes that “estimates to remediate the hazardous condition, replace the pool, and repair the damage in the lower level exceed $4 million.”

The owner of the property has already spent hundreds of thousands of dollars to remediate the issues thus far, the case—which has been viewed by Fortune—continues.

Public records detail Altman’s connection to 950 Lombard Street—a six-bed, eight-bathroom mansion with “resort-like” amenities that can accommodate more than 300 guests—after the tech mogul updated the principal address of a business interest in August 2020 from the mansion to a corporation address in Glendale, Calif.

Data from Zillow shows the property has not been sold again since.

Representatives for Altman did not reply to Fortune‘s request for comment.

A $27 million ‘lemon’

Details about the property—originally listed for $40.5 million—are not hard to come by. In fact, the property “masterpiece” was heavily advertised ahead of its sale.

When Architectural Digest visited the mansion four years ago, Gregory Malin, the CEO of developer Troon Pacific, which sold the property, proudly proclaimed the home was “extraordinarily unique” with “world class amenities.”

Malin highlighted the Russian Hill’s home’s “Batcave” entrance, art gallery, one-bed “wellness cottage” complete with spa and sauna, and glass elevator.

The four-sided infinity pool, Malin added, is one of his “favorite features” courtesy of it being suspended from the side of the property above lower levels.

The structure also came equipped with underwater speakers, meaning if visitors wanted to listen to classical music in the sprawling gardens, a swimmer could be blasting Taylor Swift beneath the surface and “no one would know,” Malin grins.

The developer also boasted, “a lot of what we do in terms of development, you can’t see.”

Here it seems Altman’s legal team would agree, saying the owner purchased what they “believed to be a beautiful, luxury home” when in fact they were sold a “$27 million lemon.”

Malin and Troon Pacific—and alleged alter egos—are being sued for unspecified damages. Neither entity responded to Fortune’s request for comment.

Further problems

Unfortunately for Altman it seems the alleged issues with the property—which spans an entire block—may be far from over.

A deck that wraps around the pool—offering views from downtown San Francisco to Alcatraz—is unintentionally buoyant.

The suit alleges that upon investigation of the pool’s defects, clogged drains were found in the adjacent decking. These drains were stuffed with sand, dirt and soil that had washed out of nearby planters and were “not able to be unclogged by commercially reasonable means.”

Ironically, the drainage and water flow system of the property was one of its crowning glories, according to Malin. This is because the home’s “drought resistant plants” and “ancient” 100-year-old olive trees were watered via a 12,500-gallon recycling cistern, making the garden “completely sustainable.”

Given the blockages in this state-of-the-art system, “inches of standing water” were found beneath the home’s deck, the complaint alleges.

Discoveries such as this, the file continues, means the owner “anticipates there are additional still undiscovered defects that plague the property and for which owner will seek damages after conducting discovery in this action.”