"Something in the water" looked different enough from all the other shark movies we've had in the past. Its a British "open water" with more characters. So in some ways was more interesting and could do more. But does it sink or swim? Unfortunately it sinks.
The movies just not very good. Most of the characters are more annoying than the screamy girl from "Jaws 2," and there are alot of unlikely things said or done in the movie. The order of deaths and when they happen is also mostly predictable.
But there are a couple of decent moments in there, and the CGI is used sparingly. But this is probably because its bad when it starts to get used more toward the end.