British Tv series/movie What is this British TV drama shown in UK from the late 90's dark swimming pool scene
I have this memory of watching I think a TV drama (possibly BBC) from the late 90's. I watched it with my mother, but I was a child then.
All I can really remember is a woman who lived in the country in a large house swimming in an outdoor swimming pool. I believe she had recently moved into this house. The pool was really murky looking, not a very nice swimming pool. Looked kind of dirty (almost black). I remember she ended up having the pool dragged and there was loads of old rubbish at the bottom of it. I remember thinking it was weird that she went swimming in it at all.
I think it was a drama TV series possibly about murder. It had a sinister tone, but I don't think it was a horror.
It's been annoying me that I can't remember it more. My mother died recently and I really wanted to find this TV show. But i'm not even totally sure that it was a TV series, it might have been a movie. But it was definitely British and I remember the pool scene. It would of been made in the 90's or very early 2000.
Would appreciate any help. Thanks