I noticed the reoccurring use of water in the movie Fatal Attraction. When they first have the affair, the water from the sink appears. Then in the rabbit scene, there is boiling water. And at the end, Alex is drowned in water (I probably forgot to mention a few other incidents). The cinematography is very clever about focusing on the water, especially on the faucets which disperse the water. What could the water be symbolizing? I know there's not an objective answer, but I'm curious to see what others think.
In order to understand the use of water in an Adrian Lyne film, you should probably look more widely at the use of water in his complete body of work. Lolita frolics under a sprinkler, Flashdance has its famous water dance, there's the bathtub scene in Jacob's Ladder, and Unfaithful has horseplay with water pistols, a car wash, a sink sponging, and a bath scene. It may be less about symbolism than about artistic preference.
Writing about his interview with Adrian Lyne regarding his "thing with water," Jeffrey Lantos says:
I seem to recall that the tide coming in was often used as a metaphor for intercourse in older films.
I cannot really remember the film but perhaps water is symbolising lust - being released from taps, becoming dangerous when boiling and becoming calm and relaxed again with the (apparent) death of Alex.
I stress that I have no expertise in this area and this is merely virtual guesswork!