I have seen a huge water clock in Yokohama, Japan. It's placed in the middle of the big hall of The Bank of Yokohama, Head Office. I went to the bank more than 10 years ago just to look at the water clock.
Here are some pictures of the water clock at the Bank of Yokohama.
This huge water clock was designed by a French physicist, Bernard Gitton. If you search the word "Bernard Gitton", you will find several pictures and videos. I haven't seen it but it seems like there is another water clock in Nagoya, Japan too. Maybe it might be somewhere near you.
Here is one of the videos of Bernard Gitton's water clock.
I was at the bank for about 10 or 15 minutes and tried to figure out how to read the time, but it was a little awkward. As you see in the picture, there is an ordinary clock on the top of the water clock as just a reminder. I don't remember it well now, but I think it moves actively at regular intervals.
This water clock is not practical, yet it has a very interesting mechanism and is artistic. More than anything, it's beautiful isn't it? You can forget the time seeing this clock even if you are looking at a clock.
