Demi Moore is being sued over the drowning of a 21-year-old man in her pool.

Demi Moore is being sued by relatives of a man who drowned in her backyard pool nearly two years ago.

Edenilson Steven Valle, 21, was found floating in the actress’ swimming pool during a party thrown at her Los Angeles home in July 2015.

Moore was out of town at the time of Valle’s death, and later told the media that she was “in absolute shock” over the “unthinkable tragedy” that had occurred in her absence.

The man’s parents, Jorge and Maria Valle, initially filed a wrongful-death lawsuit in February against the two people – including Moore’s assistant – who threw the party and the Tree House Trust, which owns her property.

However, according to TMZ, they have now added Moore as a defendant, as they allege there were "no depth markers or any safety signage" in the three-metre-deep pool.

They have also reportedly claimed that rocks around the edge that posed a trip hazard and that the pool water was at a temperature that "compromises brain function" (reportedly 38 degrees Celsius).

According to TMZ, authorities believe Valle told partygoers that evening that he couldn't swim.

TMZ understands that most of the group had temporarily left the property when he tripped and fell into the water.

He was reportedly alone at the time.