In L.A. I can tell. I lived in Washington state for a couple of years and when I got back to L.A., I could clearly smell it. As for the taste, I don't know if it's chlorine I taste, but it does taste really different. I can also really tell the difference from most Bay area, specifically Hetch Hetchy water, and L.A. municipal.

If think people can't tell the difference, you're lying to yourself.