Well you bring up an interesting point. Here's my take.

Let's adjust the definition of 'wet' a bit.
1. Having the properties of water.
2. Has water on it. (e.g. the towel is wet)

I think #1 is the appropriate one for the statement "water is wet." Clearly, water has the properties of water. It's a tautology. That being the case, I think the statement "water is wet" works just fine. "Having the properties of" is much more clear than simply "like" and avoids the confusion that you mention.