HI. I need help with a movie I saw yeeeeaaaars ago - 20 or more. This one scene has stayed with me, and I have never seen the movie since nor been able to find the title. I'm counting on you to help!

The scene that has never left me is at this indoor swimming pool in an old mansion. There are people staying at the house - not sure why or how many. In the scene, there is someone swimming in the pool when it glasses over and the person is trapped beneath. That is the only thing I remember from this movie. I hope this enough to get the title of this movie - it's been driving me crazy for a loooong time.
Thanks!