**How Long Did the Waters Prevail Over the Earth?
A Detailed Study of Genesis 7–8**
The question of how long the Floodwaters “prevailed” is central to understanding the scale and duration of the biblical Flood. Genesis gives a clear timeline, describing how long the waters dominated the earth before they began to recede. The phrase “the waters prevailed” refers to the period when the floodwaters were rising, overwhelming the land, and maintaining their domination over the surface of the earth.
This article walks through the biblical data step-by-step to show exactly how long the waters prevailed and how this fits into the overall Flood chronology.
1. What Does “Prevailed” Mean in Genesis?
In Genesis 7, the Hebrew verb gābar (“prevail” or “become mighty”) describes the waters rising, strengthening, and overwhelming the land.
This term is used repeatedly (Genesis 7:18, 19, 20, 24) to emphasize:
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Increasing depth
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Strength and force
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Complete dominance over the land
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The inability of anything alive to escape
“Prevailing” refers specifically to the period when:
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Waters were rising, and
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Waters had reached and maintained their highest level, covering all mountains.
2. The Waters Prevailed for 150 Days
Genesis gives a precise number:
“And the waters prevailed upon the earth a hundred and fifty days.”
— Genesis 7:24
This 150-day period represents the dominant stage of the Flood, from the start of the rising waters to the point when they began to recede significantly.
The 150 days include:
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40 days and nights of rain
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The continued rising of water beyond the rain period
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The waters maintaining their peak level
Thus, the waters did not stop rising after 40 days; they continued to assert dominance until the 150-day mark.
3. Breakdown of the Flood Timeline to Understand the 150 Days
3.1. First 40 Days: Rainfall and Rising Waters
Genesis states:
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Rain fell for 40 days and nights (Genesis 7:12).
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During this time, the waters rose and lifted the ark (7:17).
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The waters continued to rise even after the rain stopped.
3.2. After 40 Days: Waters Continue to Rise
The account clarifies:
“The waters prevailed and increased greatly…”
— Genesis 7:18
Even after rainfall ceased, additional waters from the “fountains of the great deep” continued contributing to the Flood (Genesis 7:11).
3.3. Total Prevailing Period: 150 Days
At the end of the period:
“God remembered Noah… and the waters began to subside.”
— Genesis 8:1
This marks the end of the prevailing period and the start of the recession.
4. Did the Waters Prevail Only 150 Days or Up to 150 Days?
Some readers wonder whether the 150 days:
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Include the 40 days of rain, or
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Begin after the 40 days of rain.
The most natural reading of Genesis supports the first view:
The 150 days include the 40 days of rain.
Why?
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Genesis 7:17 describes water rising during the 40 days.
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Genesis 7:18–20 continues describing the prevailing waters.
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Genesis 7:24 summarizes the entire period in one total: 150 days.
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Genesis 8:1 shows that only after these 150 days did God cause the waters to recede.
Thus, the 150 days represent the entire duration of rising and prevailing waters until recession began.
5. The 150 Days End When the Waters Begin to Recede
Genesis 8:1–3 describes the turning point:
“God made a wind blow over the earth, and the waters subsided…
the waters receded steadily from the earth. At the end of the 150 days the waters had gone down.”
This clarifies two key points:
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The waters did not begin to recede until the 150-day mark.
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The 150-day period includes both the rising and the maximal prevailing stage.
6. When Did the Ark Come to Rest?
Shortly after the prevailing period ended:
“On the seventeenth day of the seventh month the ark came to rest on the mountains of Ararat.”
— Genesis 8:4
This date corresponds to the point after the waters began receding but while the land remained underwater.
The ark rested during the recession phase, not during the prevailing phase.
7. Total Timeline of Floodwaters (For Context)
To place the prevailing period in the broader sequence:
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7 days waiting in the ark
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40 days of rain
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150 days waters prevail (includes the 40 days of rain)
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After 150 days waters begin to recede
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74 more days until the tops of mountains appear
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Further drying until Noah exits the ark in the following year
Thus, the waters dominated the earth for 150 days before the long recession phase.
8. Why Emphasize the 150 Days?
The number highlights:
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The totality of judgment: all land life overwhelmed.
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The completeness of divine control: floodwaters rise and fall by God’s action.
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The significance of waiting: salvation comes only after the fullness of judgment.
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Literary structure: The 150 days appear at the center of a chiastic Flood pattern (a mirrored, structured narrative form).
Conclusion: The Waters Prevailed for 150 Days
According to Genesis, the waters prevailed—rose, strengthened, and maintained control—for 150 days. This period includes the initial 40 days of rainfall and continues until God causes the waters to begin receding. The 150-day prevailing period is the centerpiece of the Flood narrative, marking the height of God’s judgment before the gradual renewal of the earth.