Alain Delon said in an interview in 2011 that he cannot watch this film again. His ex-lover Romy Schneider and good friend Maurice Ronet both died prematurely and under tragic circumstances. Revisiting the scenes are simply too painful for him.
Alain Delon and Romy Schneider had been real life partners from 1958 to 1963, they were no longer a couple when this film was shot, but remained good friends after their split. In 1966, Schneider married director Harry Meyen and had put her career on hold to care for her son David. Alain Delon imposed that Schneider should be his co-star in "La Piscine" and the film revitalized her career.
During the making of this film, Alain Delon's former bodyguard, Stephan Markovic, was found dead in a public dump, ushering the "Markovic Affair". Markovic's brother started a feud with Alain Delon and his friends, one of whom was the French President, Georges Pompidou. Both Delon and his long-standing friend François Marcantoni were questioned by the police immediately after the murder. Marcantoni was originally charged for the murder, but after further questioning by the police, he was released. Later, the drama continued when supposedly inappropriate photos of Madame Pompidou were found. Commissionaire Aimé-Blanc, who was involved in the obtaining of the photos, stated that the photos were planted by old Gaullist clans who had long-term tension against Pompidou. This led to controversy over whether the photos were real. The murder of Markovic was never solved. There were plenty people who had the motive to kill him. He was a major gambler, but it created many enemies because of the recurring theory that he would cheat. In addition, Markovic was specially known for throwing high class parties with Delon. At these parties, it is alleged that Markovic would set up cameras throughout the house, especially in the bedrooms. He gathered plenty of questionable photos of the guests, which would damage their status in society. These photos most likely were used as blackmail, especially when he approached multiple newspapers trying to sell the photographs. Surprisingly, some of these photos were alleged to be directly targeting Delon and Marcantoni. However, the most important photos Markovic supposedly had were scandalous photos of Pompidou's wife. This was a major concern to Pompidou since he was preparing to run for France's president. Alain Delon communicated with more gangsters, such as Z, Bimbo, and Petit René. Suspiciously, many of them met violent deaths after meeting Delon. However, François Marcantoni was Delon's closest Corsican gangster friend. When Delon's bodyguard, Markovic, mysteriously died, Marcantoni and Delon came under investigation. One of the factors pointing in that direction was a letter of Stevan Markovic to his brother Aleksandar where he wrote: "If I get killed, it's 100% fault of Alain Delon and his godfather Francois Marcantoni." Marcantoni was initially charged with the murder. However, after being questioned by the police, the charges were eventually dropped and the crime was never solved. As of 2016, Delon is the only member left of the Markovic affair to be still alive.
Both French and English-language versions of the film were made, with the actors filmed speaking English for the international release, which was unusual at a time when movies were always either dubbed or subtitled. That 114-minute international release, shorter than the French version, also had slightly different editing.
In 2009, the clips from the film featuring Alain Delon (along with Michel Legrand's "Le Slow de La Piscine" from the movie's soundtrack) were used in Christian Dior's commercials for Eau Savage perfume.
According to Jacques Deray in his biography, the shooting crew received as guests the two French swimming champions Christine Caron and Alain Mosconi who friendly competed a 100 yards trial in the swimming pool against the actors.