Done right you wouldn't be able to see it. Often in movies the filmmakers will add milk to the rainwater so it shows up on camera, which is probably where the "white lines" depiction of rain in games comes from in the first place.
didnt know this but makes sense i guess. I was always taught and done on my own that, you just need to light it from behind, same with smoke, steam, etc for them to show up in footage, as opposed to lighting it from the front.