Water Sort

Rules and help

Each tube holds a fixed capacity (four on early levels, five later, six on the last stretch). A board uses N colors and N+2 tubes — exactly two start empty. Every color appears exactly as many times as the tube capacity. Boards never start with a tube already filled by one color.

How to play

• Whole-block pour. The contiguous top run of one color is one block. Tap a source, then a destination. A pour is legal only when the destination is empty or shows the same top color, and its free space is tall enough for the entire block. The whole block moves; you never leave part of the run behind, and you cannot pour a tall block into a short gap.
• Win. Every tube is empty or filled with one color to capacity. There is no timer or move limit.
• Stuck. If no legal pour remains, or the only legal pour would only undo your last pour, the game tells you you’re stuck. Undo or Restart — nothing auto-restarts.
• Levels. Five hundred puzzles in chapters of twenty. Open Levels in the toolbar to pick an unlocked level. Finish a level to unlock the next. Completing level 500 leaves you on 500; Restart resets only the current board.
• Undo and Restart. Undo steps back pours within the level without limit. Restart returns the board to that level’s start and clears the undo stack.

Tips

• Guard at least one empty tube; pouring a block you cannot place again is how boards get stuck.
• Only pour when the gap fits the whole top block — a nearly full tube rejects a tall run.
• After the first easy stretch, boards stay mixed: plan ahead instead of pouring every obvious match.
• If you see “You’re stuck,” undo a step or restart; every shipped level still has a solution from the start.

Playing on a phone or tablet

Tap a tube to select its top block, then tap a destination with room for that whole block. Use Levels in the toolbar to open the chapter picker. Undo and Restart sit beside it.

Frequently asked questions

How does a pour work?

The top run of matching color is one block. You may pour it only into an empty tube or one with the same top color, and only when the free space is tall enough for the entire block. The whole block moves in one pour.

What does “You’re stuck” mean?

No useful pour is left: either nothing is legal, or the only legal pour would just reverse your last move. Undo or restart the level. The puzzle was solvable from the start.

Where is my progress saved?

On this browser only: the current level, the highest unlocked level, and an in-progress board with its undo stack. Older saves from before the current board set are ignored so the page does not break.