Solve the famous water puzzle from Die Hard 3

Tackle this brain teaser with a vengeance.

die hard 3 water puzzle
The last drop.illustration by Laura Lannes

We know you are bored at home right now—we are too. Here are some puzzles and brainteasers to challenge your family and friends with, either in person or over video chat.

Fans of Die Hard With A Vengeance will remember this one: To disable a bomb, Detective John McClane must measure out exactly 4 gallons of water, and place the resulting weight on a scale. His tools are yours: a 3-gallon and a 5-­gallon jug—and a single fountain. McClane did it in less than 5 minutes, but we won’t time you. This go-round, lives probably aren’t on the line.

Answers Below

A) Fill the 5-gallon jug. Use it to fill the 3-gallon jug, leaving 2 gallons in the 5-gallon jug. Empty the 3-gallon jug, and then pour in the 2 remaining gallons from the other jug. Fill the now empty 5-gallon jug and pour 1 gallon into the 3-gallon jug. There are 4 gallons left in the 5-gallon jug.

B) Fill the 3-gallon jug and pour it into the 5-gallon jug. Fill the 3-gallon jug again and use it to fill the 5-gallon jug. You have 1 gallon. Empty the 5-gallon jug and pour the 3-gallon jug's remaining gallon in. Refill the 3-gallon jug and pour it into the 5-gallon jug.

This article was originally published in the Summer 2019 Make It Last issue of Popular Science.