"DARK WATER" is pretty effective as a psychological thriller/horror film, but it has a small problem. It's really three movies in one, none of which plays very well with the others.

The first, and best, is something along the lines of Roman Polanski's 1965 "Repulsion." It concerns a possibly psychologically disturbed woman named Dahlia (Jennifer Connelly), whose repressed childhood traumas and nasty ongoing custody battle with her ex-husband (Dougray Scott) over their daughter, Ceci (Ariel Gade), cause her to have terrifyingly real visions involving demonic plumbing fixtures and floods of Coca-Cola-colored water in the grim apartment building she has just moved into on New York's Roosevelt Island. A Roosevelt Island, by the way, that seems to be situated not in the East River, but in Puget Sound, based on the amount of constant, depressing rain it gets. I don't think the sun comes out once in this movie, which has the nasty, gray look of something grown in a closet.

The second film is less of a peek into the cobwebbed corners of Dahlia's head than it is a more literal haunted-house story along the lines of "The Grudge" or "The Amityville Horror." There may, in fact, be an unspeakable evil lurking in Dahlia's high-rise, and it may involve -- grab onto your cup holder -- a person or persons no longer living.

The third movie, and in every way the silliest one of the bunch, is a cautionary tale about the difficulty of finding a good apartment -- sort of a nightmarish "Mr. Blandings Builds His Dream House" for renters. Forget Dahlia's putative hallucinations (are they real or aren't they?). Forget the restless ghost story. Although it's never entirely clear what the extent of the problem is, one thing is certain. There is, in fact, a nasty leak in Dahlia's bedroom ceiling, not to mention one in the elevator, which seems to have a mind of its own. And the water in her tap is as likely to come out brown as clear.

Oh, and then there's the creepy building superintendent (Pete Postlethwaite), a man named Veeck who seems, by his accent, to have come from the Bronx via Transylvania and who, along with the cheery but ineffectual building manager (John C. Reilly), conspires to keep Dahlia from ever getting that doggone leak fixed.

But Dahlia's problems run deeper than dirty, dripping water. Shortly after mother and daughter move in, Ceci starts having conversations with an imaginary friend. (Yeah, I know. I've heard that one before, too.)

There are, to be sure, pleasures to be had here, most of which have more to do with style than substance. Director Walter Salles ("The Motorcycle Diaries") drapes a nice sense of gloom and foreboding over the proceedings, while Connelly brings real class (along with strength and vulnerability at palpable odds with each other) to what is effectively a damsel-in-distress role.

Still, there's something that never quite works about the film, which can't seem to decide if it's all in Dahlia's head, all in the spirit world or all in her pipes. As my friend J.J. said, in a commentary that will resonate with drinkers of lead-plagued Washington water, maybe Dahlia should just get herself a Brita and be done with it.

DARK WATER (PG-13, 102 minutes) -- Contains some obscenity and disturbing images. Area theaters.

A good apartment building is hard to find: "Dark Water's" John C. Reilly, left, Jennifer Connelly and Ariel Gade.