The shot was taken at night. I should have done the shot in daytime (where the colour saturation would have been nicer anyway). But working does mean not having time in the day to do any shooting...
I tried cropping away the drain but the unequal length of the black and white strip seems a bit unnerving to me. I also tried to crop to a panorama so that the black and white becomes equal but it looks even worse, so I decided to keep the drain.