Water Sort is a pouring puzzle: tubes filled with layers of coloured liquid, jumbled, and your job is to get every colour into a tube of its own. This version runs in your browser, free, with no download and no signup — you tap one tube to lift it and another to pour. It starts at four colours and climbs to nine, and it rewards planning two pours ahead rather than fast tapping.
How to Play Water Sort: The Rules in 60 Seconds
Level 1 gives you six tubes: four of them are filled with a jumble of four colours, two are empty. Every tube holds exactly four units of liquid, and every colour appears exactly four times on the board — that arithmetic never changes and it is the single most useful fact in the game. Tap a tube to lift it, tap a second tube to pour. Tapping the lifted tube again puts it back down.
There is one legal-move rule, and it has two halves. You may pour onto a colour only if it is the same colour already sitting on top of the destination, or if the destination is completely empty. The destination also has to have room. So no, you cannot pour red onto blue, ever — not to "make space", not as a temporary parking spot. An empty tube is the only container that accepts anything.
The part that catches new players: a pour moves your whole top run at once, but only as much as fits. If you have three reds stacked on top and you pour them into a tube with one slot free, exactly one red moves and your run of three is now split across two tubes. Clear the level by getting every tube to be either empty or four units of one colour — a green tick appears over each finished tube, and a finished tube can no longer be picked up as a source. There is no timer and no move limit, so the only thing that can end a level is running out of legal moves. Each clear is worth 50 points plus 10 per colour on the board (90 on level 1, 140 once you reach nine colours), and a new colour is added every second level up to nine colours in eleven tubes.
Stuck With No Moves Left? Here's How to Get Out
First, separate two things that feel identical but are not. "Stuck" means you cannot see a good move. "Dead" means the board has no legal move at all: no tube is empty, no tube has room under a matching colour, and every exposed top colour is different from every other top colour that has space. The game only ends on the second one. If any two tubes show the same top colour and the receiver is not full, you are still alive, even if the move looks pointless.
Every level restocks three undos, one hint and one extra tube, all free and all reset when the next level loads. The undo button steps the whole board back one pour at a time, so three undos gets you back three moves — enough to reverse a bad chain, not enough to rethink an entire level. The hint highlights two tubes for a couple of seconds, and it is a heuristic rather than a solver: it looks first for a pour that completes a tube, then for a merge of two same-coloured stacks, then for a mixed tube worth emptying. It shows you a good move, not the winning line.
The thing worth remembering above all else: those three buttons only work while the board is alive. The moment your last legal move disappears, the run ends and the buttons go dead with it — you cannot undo your way out of a deadlock or add a tube after the fact. So the check to run before every pour into an empty tube is: after this, will any two tops still match? If the answer is no and this was your last empty, that is the moment to spend the extra tube, one move early, not one move late.
Are All Water Sort Levels Actually Solvable?
Yes — every level here starts solvable, and that is guaranteed by how it is built rather than by testing. The generator starts from the finished board (each colour already neat in its own tube), then plays forty-odd legal pours backwards to scramble it. A position reached by rewinding a solution always has a solution: retrace those pours forwards. So if a level looks impossible on move one, it isn't. You are looking at a shuffle you haven't cracked yet.
What is not guaranteed is that it stays solvable. Nothing stops you from making moves that destroy the solution, and the classic way to do it is to spend both empty tubes on single units early — one orange here, one purple there. You now have two tubes that each hold one unit of a colour whose other three units are buried under different colours, and the eight units of free space you started the level with have shrunk to six with nothing gained. That board can still be legal for a long time before it strands you, which is why deadlock usually feels sudden and is actually about ten moves old.
There is also no shortcut formula that tells you whether an arbitrary jumble is winnable — researchers who studied these puzzles found water sort and ball sort to be the same problem mathematically, and the general problem is computationally hard, so brute inspection is genuinely the honest method. One practical consequence for this version: levels are generated fresh every time you play, so "level 9" is not the same board twice, and no walkthrough video for a mobile app will match what is on your screen.
Five Habits That Clear Hard Levels
Count to four. Every colour has exactly four units on the board, so if a tube already shows three yellows, exactly one yellow is hiding somewhere — go find it before you touch anything else. Reading the board this way turns a wall of colour into a short list of specific errands, and it tells you which tube you actually need to dig into rather than which one looks messiest.
Pour big runs, never singles. Since a pour carries the entire top run, moving three units in one action costs you the same one move as moving one. Dropping a single unit into an empty tube spends a quarter of your total free space to relocate one quarter of one colour — the worst exchange rate available. Related habit: match the space to the run. Before pouring, check the destination has room for the whole run, otherwise you split the run in two and will pay a move later to reunite it.
Keep one tube completely empty for as long as you can, and treat the second empty as the one you are allowed to spend. A fully empty tube is the only universal receiver in the game; the moment both are occupied, your options collapse to colour matches only. Finally, look at what a pour uncovers, not just what it tidies. The best move is often the one that exposes the fourth unit of a colour you are already three-quarters done with, even if the tube it leaves behind looks worse than before.
When the Extra Tube Is Worth It (and When It Isn't)
You start each level with eight units of free space — two empty tubes, four slots each — no matter how many colours are in play. The extra tube adds four more, so it is a 50% increase in your working room, which is a much bigger deal than a small button implies. It costs nothing: one per level, refreshed automatically at every new level, with nothing to buy or watch anywhere in this game.
Mechanically it is also the one guaranteed escape. An empty tube accepts any colour, so the instant you add one, at least one legal pour exists again — a board that was one move from death is alive. The catch is timing, and it is unforgiving: once the last legal move is gone, the run is over and the button is disabled with everything else. Add the tube while you can still move, at the point where you can see that your next pour will strand you, not after.
The wrong time to spend it is early, on frustration. If you press it on move three because a colour is buried, you have converted your endgame slack into mid-game convenience, and the crunch in Water Sort is almost always at the end, when three colours are half-sorted and every top is different. It also will not save a board you have already shredded — if a single colour is sitting in four separate tubes as four singletons, one extra tube postpones the deadlock rather than fixing it. That is an undo situation, not a tube situation.
Water Sort vs Ball Sort vs Nut Sort: Same Puzzle, Different Skin
Underneath the art, these are one puzzle: containers with a fixed capacity, tokens in a handful of colours, and a legal move that lifts the top item onto a matching top or into an empty container. Water Sort dresses it as liquid in test tubes, Ball Sort as coloured balls in glass cylinders, Nut Sort and Screw Sort as bolts threaded onto rods. If you can read one board, you can read all of them, and the counting habit transfers unchanged.
The mechanical difference that actually changes your strategy is how many items move per tap. Liquid pours as a run: three stacked reds leave together in one action, which is why run length dominates water sort planning. Most ball sort versions move a single ball per tap, so that same stack costs three moves — slower, but it gives you deliberate control over splitting a stack, a thing water sort will not let you do on purpose. Nut and screw variants add something water sort never has: hidden information. Bolts sit under plates or on covered rods, so you are planning around colours you cannot see yet, and many of them add a limited buffer that fills up.
That buffer is also a second way to lose. Our Screw Sort at /puzzles/screw-sort/ ends when wrong-coloured screws overflow the holding area, whereas Water Sort can only ever end in deadlock — there is no clock and no capacity to blow. If you like the sorting loop but want the pressure of a resource draining while you think, that is the one to try next; if you want the version where the whole problem is visible from move one and the only enemy is your own move order, you are already on the right page.
Questions people ask
Can I pour any colour onto any other colour?
No. A pour is legal only if the top of the destination tube is the same colour as the top of the tube you are pouring from, or if the destination is completely empty and has room. There is no way to stack red on blue, even temporarily, which is why the empty tubes are so valuable — they are the only containers that will accept anything.
Why did only one unit pour when I had three of that colour on top?
Because a pour moves your whole top run but is capped by the space available. Three reds poured into a tube with one free slot moves exactly one red, and your run is now split across two tubes. Check the destination's free space before you pour: if it can't take the whole run and you didn't intend the split, find a different target.
Is this level impossible, or am I missing something?
Every level starts solvable — the board is built by taking a finished puzzle and playing legal pours backwards, so a solution always exists at move one. What can happen is that your own moves make it unwinnable, usually by spending both empty tubes on single units early. If you are stuck, undo back to before you emptied your last free tube.
Do I have to pay or watch an ad to get an extra tube?
No. You get one extra tube, one hint and three undos on every level, all free, and all three restock automatically when the next level loads. Nothing in this game is for sale. Just use the extra tube before the board deadlocks — once no legal move remains the run ends and every button is disabled.
Does my progress save, and do I need an account?
No account and no signup. Your best score is stored locally in your browser, and the results screen shows the level you reached, but the level you are currently on doesn't carry over — closing the tab ends that run. Boards are generated fresh each time you play, so you will never get the exact same jumble twice.
How to play Water Sort
- Tap a tube to pick it up, tap another to pour.
- You can only pour onto the same colour or into an empty tube.
- Sort every colour into its own tube to win the level.
Water Sort is free to play online at Trivio — no download, no signup, works on desktop and mobile. Your best score is saved in your browser.