Is there a compound that contains water as a subcomponent?
Off the top of my head: Coordination complexes that have water ligated to a (transition) metal atom.



See corresponding Wikipedia article
A familiar example would be (hydrated) copper sulfate $\ce{CuSO4.5H2O}$, which has 4 water molecules ligated to the copper atom. (The fifth water molecule mentioned in the chemical formula is associated copper sulfate via hydrogen bonds)




 The picture is sources from the Wikipedia article for copper sulfate, and the diagram is sourced from this Quora post 

If you're new to the idea of complex ions, this chemguide article offers a good intro to the topic.