Brain teasers like this are a fun way to test your observation skills. At first glance, it looks like all five cups are connected, making it difficult to predict which one will fill first. But if you carefully trace the pipes, only one cup has the quickest unobstructed path.

The Puzzle

A teapot pours liquid into a network of pipes connected to five cups labeled 1–5.

The question is simple:

Which cup will fill first?

Take a moment to follow each pipe before reading the answer!

Let’s Analyze the Pipes

The trick is not to guess—it’s to trace the flow step by step.

• Cup 1 has a longer side path.
• Cup 2 depends on a lower branch that doesn’t receive water first.
• Cup 4 is connected through a side pipe that only fills after the main pipe reaches that level.
• Cup 5 has the longest route of all.
• Cup 3 sits directly beneath the main vertical pipe, receiving water without any unnecessary detours.

Since water always follows the available path downward, the shortest open route fills first.

✅ Correct Answer: Cup 3

Cup 3 is the first cup to fill.

It is connected directly to the main vertical pipe, allowing water to reach it before any of the longer side branches can fill the other cups.

Why Many People Get It Wrong

Many people immediately focus on the cups closest to the outer pipes, assuming Cup 1 or Cup 5 will fill first because their pipes seem obvious.

However, this puzzle is all about following the actual flow, not judging by appearance.

The shortest unobstructed route always wins.

The Secret to Solving These Puzzles

Whenever you see a “Which cup fills first?” puzzle:

• Start from the source of the liquid.
• Trace each pipe carefully.
• Watch for blocked or longer routes.
• Compare which open path reaches a cup first.
• Don’t rely on visual intuition—follow the connections one by one.

Final Answer

🏆 Cup 3 fills first.

Did you choose Cup 3, or did one of the side paths trick you? Let us know your answer in the comments before checking what everyone else picked!