Which Sumerian text are you referring to?

If you're referring to the Atrahasis myth, yes and no. It's clear that there is some sort of general ANE flood myth (Noah, Atrahasis, Utnapishtim). Nobody in mainstream scholarship (whether conservative, liberal, or centrist) really disputes that, as any introductory textbook to the Hebrew Bible would tell you. See Collins' An Introduction to the Hebrew Bible, for example.

However, what is not immediately clear is whether or not the OT directly "borrows" these texts, or simply culls from the already well known story. While the OT certainly does have links to other pieces of ANE literature, it's not necessarily the case that these pieces of literature proper were being copied. In my view, just because you have a parallel in another piece of literature doesn't mean that it's necessarily one copying from the other; see Samuel Sandmel's article "Parallelomania" for a very interesting and enlightening discussion.

I guess, to answer your question in a more direct way, there are far better explanations for the OT flood myth than a simple literary dependence of the OT upon a Sumerian text. The OT was written primarily in an oral culture, one in which stories were primarily communicated verbally, rather than via the written word (as the vast majority of the population was illiterate). The book to read on this is The Flood Myth, ed. Alan Dundes.