The flood narrative is made of two different, often clashing, stories woven together.
Finding the story of the flood in the Bible is a rather problematic matter. This is not to say that anyone interested in it has to read between the lines and gather a bunch of obscure allusions to some primeval deluge and then rebuild the story himself. The myth is easily found in chapters 6 to 9 of the book of Genesis. And most people are more or less familiar with it. The story begins with God’s decision to return the Earth to its pre-creation chaos — when the “Spirit of God was moving over the face of the waters” (Cf. Gn 1, 1) — with Noah and his family being in charge of assisting in this new beginning.
Difficulties arise when the reader notices there are two different versions of the myth in just a few pages. But this is far from being surprising. The Bible often provides the reader with contradictory storylines referring to more or less the same things. This is especially the case with what scholars call the “primeval history” — the first 11 chapters of Genesis. There is a relatively obvious reason for it. These opening chapters are all filled with fable-like, deeply symbolic elements. For example, most of the names of its characters and geographic references are figurative and representational rather than real — Adam literally meaning “mankind” but also hinting at adamah, “earth”; Eve meaning either “living one” or “source of life;” the famous “Land of Nod” east of Eden where Cain was exiled meaning “wandering.” Most of these stories always refer to the “first” something: the first human beings, the first murder, the first empire. The flood narrative is, in a way, a revisiting of the “first,” primeval waters. That is, these are ancient stories, and it is no wonder they have been told differently throughout millennia.
How long did the flood last, according to the Bible?
The Bible provides two different answers to that question. In short, the whole flood narrative is made up of two stories woven together, each one corresponding to a different source. Naturally, they will eventually contradict each other here and there. For example, they disagree regarding how many animals were supposed to be taken aboard the ark. Chapter six says “one pair of each” (Cf. Gn. 6:19). Chapter seven says “one pair of the unclean animals and seven pairs of the clean” (Cf. Gn. 7:2). One also finds Noah releasing a raven which “went to and fro until the waters were dried up” and a dove which on the third occasion “did not return to him again.”
But, perhaps the most striking difference between both stories is how long the flood lasted. Chapter seven says two different things, just a few verses separating both versions. According to Genesis 7:17 the flood lasted 40 days. This is, surely, the most famous version of the story. It has been the subject of all kinds of symbolic, typological, theological interpretations — these 40 days being read as a prefiguration of the 40 years the Israelites spent wandering in the wilderness, and of Jesus’ 40 days in the desert.
But according to Genesis 7:24 — just seven verses later — the flood lasted 150 days. How can this difference be explained?
The answer is relatively simple. Scholars agree the 40-day narrative is the original one. It focuses on Noah’s righteousness rather than in God’s majesty and power. Hence, the duration of the flood is more “modest” — in fact, it takes only one week to recede: it is conceived in more “human” terms. The 150-day story is a later addition. It highlights God’s transcendence, justice, and virtue: it is a more “godly,” “divinely” oriented one.Both of them, together, form a unified whole that provides the reader with a comprehensive understanding of the requirements of divine justice and the human righteous answer to such demands.