The structure has a waterproof material that makes it not likely to leak water. In this context, I think it's more common to use the word "material" as a noncountable noun. Therefore, it would not require an article. CORRECTIONS: The structure is made of waterproof material that makes it unlikely for it to leak. OR The structure is made of waterproof material making it unlikely to leak. (I prefer the second one.) The str

I think it's okay to say aloud, but it seems a little odd in writing. I might write, "I'll take the risk. The structure has a waterproof material that makes unlikely to leak water."

I don't know if this is properly written.

It is a pot made of a waterproof material. It takes plants and you water them. If you water too much, the water can start to leak.

Is your intention is to talk about water entering the structure not exiting the structure? For example water entering a tent. Not water exiting a water container. Is that right?