It’s hard to fathom the amount of rain Hurricane Harvey dumped on Texas and Louisiana. Some weather stations in the region recorded more than 50 inches (over 4 feet!). It’s a once-in-1,000-years flood. And the consequences have been catastrophic: At least 46 are dead, around 30,000-40,000 homes have been destroyed, and 35,000 people relocated to emergency shelters. The recovery is expected to cost well more than $150 billion, and it will take years to complete.

It’s all because over six days, 27 trillion gallons of water fell over Texas and Louisiana, as Ryan Maue, a meteorologist with WeatherBell, told CNN. (The calculation is simple, he says on Twitter: It’s depth of rain multiplied by the number of square miles covered.) That’s one million gallons of water for nearly every person who lives in Texas. For reference, here’s what one million gallons of water looks like hovering above an average-sized person.

Twenty-seven trillion gallons is much harder to fathom. To help, we wondered what 27 trillion gallons would look like in one giant raindrop. Its size is reminiscent of a mushroom cloud.

Harvey’s total rainfall dwarfs the amount of rain dumped over Louisiana and Mississippi during Hurricane Katrina in 2005. That storm produced 6.56 trillion gallons over those states, the Washington Post’s Jason Samenow explains. (Which goes to show how different Katrina and Harvey are. Katrina brought destruction via storm surge and the crumbling of New Orleans levees. Harvey stalled over the coast after making landfall.)

For reference, here’s Harvey’s rainwater over Manhattan:

And over Washington, DC: