Thank you! that's awesome, always happy to hear about people having fun and doing cool stuff with the assets!
The default water tile would just be a plain blue 16x16 tile, to be honest! I'm not sure why I didn't include it, but I will include it in the next update, as I've been asked about it before. In the meantime, I'll include it here, you should be able to right-click and save it.
