In Roman Polanski’s Chinatown (1974), private investigator Jake Gittes (Jack Nicholson) begins following the case of a Mr. Mulwray, a big shot in the Los Angeles water department in the 1930’s who has drowned – ironically, during a drought. The water department is a far more important focus in LA than in most cities. As LA is in the middle of a desert, water has always been a highly valued (sometimes scarce) commodity and a central concern to its residents. Gittes’ initial investigation, supposedly to discover whether Mulwray was unfaithful to his wife Evelyn (Faye Dunaway), leads Gittes to the LA waterway where Mulwray’s body was found and where Gittes finds himself attacked by thugs, one played by Polanski himself. Getting involved in the city’s water situation is a dangerous enterprise in this movie.
Gittes eventually stumbles on a scheme to divert water from the San Fernando Valley, buy the land cheaply, and then divert water back to make the land profitable. The trail leads to Evelyn’s wealthy father, Noah Cross (John Huston). Cross, we learn, is the big bad man behind this corruption, while his murdered son-in-law was a good man who wanted to help the city and suffered the consequences of finding out about the deception.
Water is life – both symbolically, as depicted in countless examples of literature and art throughout history, and literally, as human beings die without constant consumption of water. Mulwray wanted to preserve the life of his fellow LA residents and stave off the dangers of the desert, a life-killing landscape metaphorically linked to the evil of Noah Cross. The choice of the name “Noah” is another touch of irony, since Noah in the Bible preserved life during a flood while Noah Cross does the opposite, aggravating a drought and killing for profit. In one scene, Gittes eats at Cross’ place and is served a whole fish. The oversized seafood dish emphasizes Cross' act of taking life out of the water and forcing creatures who need water to dry up without it.
After being told that there was salt water in Mulwray's lungs when he died, Gittes discovers there is salt water in the pond at Mrs. Mulwray's house. Gittes realizes that Cross drowned his son-in-law in the pond, again illustrating Cross’ evil via his relationship with water – water is the source of life, yet Cross uses it to end life. Morever, he ends the life of a family member, just as he does not respect family bonds in his incestuous relationship with his daughter. By setting Cross’ repulsive murder within a body of water, the film conveys that the corrupt magnate is a foul plague that threatens the very existence of life itself.