Rules
Pipes is a pipe-connecting puzzle. Each cell is a tile with openings toward its sides. Turn the tiles so every opening meets a neighbour. Two tiles meet when each opens toward the other. An opening that runs off the board is a loose end. An opening that faces a neighbour which does not open back is a loose end too. The puzzle is finished when the pipes are one tree: every tile is connected, nothing loops, and nothing is a loose end. Pipes do not wrap around the edges. You can lock a tile you already trust. A lock is your mark. The puzzle does not start with any locks. While you play, an unlocked loose end stays quiet. Tiles on a loop are marked whether or not they are locked. A locked opening off the board, two locked neighbours that disagree, and a locked group that cannot grow to fill the board are marked too. Play and print are 5×5, 6×6, 7×7, 8×8, 9×9, 10×10, 7×9, and 6×8, each at easy, medium, and hard. The daily puzzle is a 7×7 easy grid. People also look this up as a pipes puzzle, a net puzzle, or a pipe connect puzzle.
- Meet a neighbour. Each cell is a tile with openings toward its sides. Two tiles meet when each opens toward the other.
- One tree. The grid is finished when every tile is connected, nothing loops, and nothing is a loose end.
- Locks are yours. A lock freezes a tile you already trust. The puzzle starts with no locks.
An end has one opening, a straight has two opposite openings, a corner meets, and a tee has three. The frame is the solved frame. The pipes are teal. No locks. No yellow. No small square on the centre cell. A printed answer draws the solved turns and that square, in black and white. A printed puzzle page shows the scrambled tiles and no square. Print pages cannot show the yellow, the coral, or the teal.
- Pipe
- Lock
- Loop
Choose Rotate or Lock under the board. Rotate starts selected. Tap a tile to turn it clockwise a quarter turn. Hold the tile, or right-click it, to turn it the other way. That backward turn still works while Lock is selected, and only when the tile is unlocked. A drag that leaves the tile does not turn it. In Lock, tap a tile to freeze it, and tap again to unlock it. A locked tile does not rotate. Arrow keys move the cell cursor and stop at the edge. The first arrow, when nothing is selected, selects the top-left cell and does not turn it. A turns the selected tile counter-clockwise.D turns it clockwise. F turns it halfway, and undo steps one quarter at a time. S locks or unlocks. The keys1 and 2 select Rotate and Lock.
The line under the board is "Tap rotates. Hold or right-click turns back. Lock freezes a tile." Once the grid is solved, that line is "Every pipe meets, and the grid is one tree."
Press Hint for one step the pipes already force, with a sentence saying why. Hint lights the cells it uses, turns the tile when it has to, and locks it. One press writes one tile and stops. Press Check when you want the board checked. A legal unfinished board gets "No mistakes so far. Keep going!" A broken board gets "Something breaks the rules. Look for the marked loop." Hint on a broken board gets "This board has a mistake, so there is no hint yet." If Hint finds nothing on a legal board, it says "No forced turn from here. A tile may be wrong, so try Check or Undo." Undo and Redo step through the turns and the locks. A hint's turn and lock undo together. Reset returns every tile to the start and clears the locks. When the tree is complete, the pipes turn teal. The dialog title is "Solved!" The dialog body is "Every pipe meets, and the grid is one tree." The Mistakes counter counts how many times Check found a broken board. It is not a score.
A coral pipe is a loop, a locked opening off the board, two locked neighbours that disagree, or a locked group that cannot grow. With error highlighting off, none of that coral is drawn. The picture of a finished grid in this article draws the solved pipes and leaves every tile unlocked. It does not draw the small square a printed answer puts on the centre cell.
One turn
A tile with one turn left is locked. On a blank easy grid that turn is already fixed before you lock anything. Hint writes the first such tile in reading order and stops. The toast is always "Only one turn of this tile is still possible." It does not say that a side leaving the board is closed, and it does not say that every remaining turn agrees. On this easy grid Hint writes the corner end before the edge tee, because both turns are already fixed and the corner is first. The edge picture is drawn with that corner already locked. The corner press is drawn in the section after that picture.
Off the board Easy
A side that would leave the board is closed. That side of the tile is already fixed. On this grid the corner end is already locked, pointing east. Hint wrote that corner first. This press is the tee beside it, at row 1 column 2. The tee is showing north, south, and west. Three of its turns open north, off the board. The only turn that stays on the board is east, south, and west. The press turns the tee three quarters clockwise and locks it. The corner's opening is not what removes those three turns.
The yellow wash sits on row 1 column 2 only. The new pipes are yellow, with the lock icon. The corner stays locked and is not yellow. The grid is still unfinished. Pipes that already meet, at row 2 columns 1 to 3 and row 3 columns 3 and 4, stay teal. The new lock is not in that set. Hint does not use the sentence about the board edge. The toast is "Only one turn of this tile is still possible." This is the second press, not the opening. It does not finish. Easy, medium, and hard all give this hint, and so does a label outside those three.
The tee turns to east, south, and west, and locks. Yellow sits on row 1 column 2 only. The corner lock has no wash. The pipes that already meet stay teal. The grid is still unfinished. Hint says "Only one turn of this tile is still possible."
The sides agree Easy
Every remaining turn of this tile agrees on this side, so the side is fixed. A neighbour has to meet it. On this blank grid the end at row 1 column 1 is showing north. North and west leave the board. East and south would stay on the board. The tee beside it has only one turn that stays on the board, east, south, and west, and that turn opens west. The end has to open east. Pointing south cannot meet that tee. The press turns the end one quarter clockwise, from north to east, and locks it. The tee is still showing north, south, and west. Hint writes this corner before it writes the tee, because both turns are already fixed and the corner is first.
The yellow wash sits on row 1 column 1 only. The new pipes are yellow, with the lock icon. Nothing else is locked. The grid is still unfinished. This is the opening press. Hint does not say the agree sentence. On these walks that sentence never came up as the toast. That does not mean the check is missing. The toast is "Only one turn of this tile is still possible." Easy, medium, and hard all give this hint, and so does a label outside those three. It does not finish.
The corner end turns from north to east and locks. Yellow sits on row 1 column 1 only. The tee beside it is still showing north, south, and west. The grid is still unfinished. Hint says "Only one turn of this tile is still possible."
The same sentence fixes a tile that is not on the edge. On this grid, after the first six locks, the straight at row 2 column 2 is still showing east and west. The locked tee above it opens south, so the straight has to open north. East and west cannot. The press turns it one quarter, to north and south, and locks it. It was already the only remaining turn on the blank grid. The locks above it are what a reader can see. The six older locks have no wash.
Before the press the straight is teal, because it meets the pipes through the centre. After the press it points north and south, it drops out of that set, and it is yellow. The toast is the same one-turn sentence. This press does not finish.
The straight turns from east-west to north-south and locks. Yellow sits on row 2 column 2 only. It was teal and leaves that set. The six older locks have no wash. The grid is still unfinished. Hint says "Only one turn of this tile is still possible."
Already joined
When two tiles are already on the same pipes, the side that would join them again has to stay closed. Opening it would loop. Hint writes that tile and names one locked neighbour. The neighbour in the picture is the tile above, and they do meet. The side that stays closed is the side below, and that lower tile is not highlighted. A blank grid in this set does not open here. Every medium walk opens on one turn.
Keep that side closed Medium
Two tiles that are already on the same pipes must not be joined a second time. On this grid the tee at row 2 column 4 is showing north, east, and south. The locked tile above it opens south, so the tee has to open north. The locked tee on its left opens east, so it has to open west. That leaves two turns: north-south-west, and north-east-west. The tile below, row 3 column 4, is already on the same pipes as this tee. Opening south would loop. North-south-west is the turn that opens south, so it goes. The press turns the tee three quarters clockwise, to north, east, and west, and locks it.
The yellow wash sits on row 2 column 4 and on row 1 column 4. Those two tiles meet: row 1 column 4 is a locked east-south corner and opens south. The side that stays closed is the south side, between row 2 column 4 and row 3 column 4. Row 3 column 4 is not yellow. There is no path of cells drawn around the loop. The pipes light every cell except row 3 column 5, before and after. Row 2 column 4 and row 1 column 4 are yellow on top of that teal. Row 1 column 4 keeps its lock. The new lock icon is on row 2 column 4. The toast is "These two tiles are already connected, so this side must stay closed or it would loop."
This is not the opening. The opening on this grid was a lock of row 1 column 1 with no turn. The tile here does turn. Easy, medium, and hard all give this hint, and so does a label outside those three. It does not finish. One later press in the whole set, on an 8×8 medium grid, finishes with this sentence, and the live button skips the toast. That press is not drawn.
The tee turns to north, east, and west, and locks. Yellow sits on row 2 column 4 and on the locked corner above it. The tile below is not yellow. The grid is still unfinished. Hint says "These two tiles are already connected, so this side must stay closed or it would loop."
A turn that cannot cover
A turn can be impossible because it would join pipes that already meet, or because every open end of that turn runs into a group that cannot cover the board. Hint says one of those sentences and stops. On the grid below, the meeting turn comes first, and the too-small group is the next press. The sentence about a limited group on its own never writes. When both limits fire, Hint still says the group is too small. It does not use a third name. A hard grid in this set still opens on one turn. Hint does not hide these sentences on an easy label.
Two pipes already meet Hard
A turn that would join two pipes that already meet is impossible. On this grid the tee at row 4 column 2 is showing north, south, and west. The tee on its right, row 4 column 3, still has two turns that open east. Each of those turns runs into pipes this path already reaches, so both are impossible. The two turns that remain both open west, toward row 4 column 2. This tee has to open east. North-south-west does not, so it goes. The press turns it one quarter clockwise, to north, east, and west, and locks it.
Do not look for two arms of this tee that meet each other. The tile on the right loses the turns that open east, and this tee then needs its east side open. The yellow wash sits on row 4 column 2 only. Row 4 column 3 is not yellow, and it stays east, south, and west, unlocked. The grid is still unfinished. Before the press the lit cells are row 1 column 5, row 2 column 5, all of row 3, and row 4 columns 1 and 2. After the press the lit set also takes row 4 columns 3 to 5 and row 5 columns 3 and 4. Row 4 column 2 is yellow on top of that teal. The toast is "This turn would join two pipes that already meet, so that turn is impossible."
This is not the opening. The first twelve presses on this grid are the one-turn sentence. Easy, medium, and hard all give this hint, and so does a label outside those three. It does not finish. A later pass would also see the group that is too small. Hint stops at this sentence.
The tee turns to north, east, and west, and locks. Yellow sits on row 4 column 2 only. The tee on the right is not yellow. The grid is still unfinished. Hint says "This turn would join two pipes that already meet, so that turn is impossible."
Too small to cover the board Hard
A turn can leave every open end in a group that is too small to cover the board. On this same grid, the next press is the end at row 3 column 1. It is showing south. North is closed, because the locked end above it points north. West leaves the board. South and east are still open. The corner under it, row 4 column 1, is left with only east and south. That turn does not open north. The tile under the corner is what forces that: it opens north, so the corner cannot point south and still meet it. Pointing the end south would face a corner that does not open back. The press turns the end three quarters clockwise, from south to east, and locks it.
The south side closes, and the toast is still the too-small sentence, because that pass is the one that found the group. The yellow wash sits on row 3 column 1 only. The corner under it is not yellow. Before the press the lit set includes that end. After the press the end points east and drops out of that set. It is yellow, not teal. The toast is "Every open end of this turn runs into a group that is too small to cover the board."
Hint can also say "Coming this way can reach only a limited group of tiles." That is the case where one limit fires and the other does not. On these grids that sentence never writes. That does not mean the check is missing. There is no picture for it. When both limits fire, Hint still says the group is too small. It does not announce a third name, and there is no picture for that pair.
This press is the one after the meeting turn. Easy, medium, and hard all give this hint, and so does a label outside those three. It does not finish. The 9×9 hard grids in this set do not say this sentence. They do say the meeting turn, and they do say the side that stays closed. Not every hard grid says the group is too small.
The end turns from south to east and locks. Yellow sits on row 3 column 1 only. It leaves the teal set. The corner under it is not yellow. The grid is still unfinished. Hint says "Every open end of this turn runs into a group that is too small to cover the board."
Common mistakes
Check paints a broken rule. Hint will not explain a board that is already broken. The toast is "This board has a mistake, so there is no hint yet." Check says "Something breaks the rules. Look for the marked loop." even when the mark is not a loop. A wrong lock, or a wrong turn you have not locked, can also sit there with no coral at all. Then Check says "No mistakes so far. Keep going!" If the wrong turn did not remove the next step, Hint still offers that step. The wrong tile stays unless that step writes it. If the wrong lock removed the only step, Hint says "No forced turn from here. A tile may be wrong, so try Check or Undo." The button does not call the hint on a broken board. The figures of a broken board do not draw yellow.
Row 1 columns 3 and 4, and row 2 columns 3 and 4, meet in a cycle. The shapes are legal turns of the scramble, and nothing is locked. Coral sits on those four cells and nowhere else. Check says "Something breaks the rules. Look for the marked loop." Hint shows the error toast and does not draw the opening turn.
The tee at row 1 column 2 is locked while it still opens north. Coral sits on that tile only. No yellow. Hint says "This board has a mistake, so there is no hint yet." Check still says "Something breaks the rules. Look for the marked loop."
Row 1 column 1 points south, and the tee beside it opens west. The end does not open east. Coral sits on both tiles. There is no locked opening off the board, and no closed group. No yellow. Hint says "This board has a mistake, so there is no hint yet."
A locked pair that meets only itself is marked, and so is every tile shut out of that pair, so the live board paints the whole grid. On this grid the only such pair is row 4 column 4 pointing east and row 4 column 5 pointing west, both locked. That wash is not drawn. A sealed group is marked.
The straight at row 2 column 2 is locked while it still runs east and west. Its solution runs north and south. The lock does not make a loop, a border, a mismatch, or a closed group. No coral. No yellow. The lock icon is ordinary ink, on the soft well. The pipes stay violet, or teal where they already meet. Check says "No mistakes so far. Keep going!" Hint says "No forced turn from here. A tile may be wrong, so try Check or Undo."
The tee at row 1 column 2 has been turned to north, east, and west, and left unlocked. The board is still legal. Hint's opening press still locks the corner, pointing east. The wrong tee stays. Yellow sits on the corner only. No coral. Check, before or after that press, says "No mistakes so far. Keep going!" The next press would turn that tee halfway, to east, south, and west, and lock it. That press is not drawn.
What to play next
Easy grids follow from one tile at a time. A side that would leave the board is closed. A side that every remaining turn shares is fixed. When one turn is left, lock it. Hint uses that one sentence for all three. Start on a 5×5 easy grid, or on the daily 7×7 easy grid. Medium grids add the side that must stay closed because the pipes already meet. A medium grid still opens on one turn. Hard grids add a turn that would join pipes that already meet, and on some sizes a turn whose open ends cannot cover the board. A hard grid still opens on one turn, and it can come back to the one-turn sentence. The 9×9 hard grids in this set say the meeting turn and the closed side. They do not say the group is too small. The sentence about a limited group on its own does not come up on these grids.
A printed puzzle page shows the scrambled tiles. A printed answer draws the solved turns and a small square on one cell. Four 5×5, 6×6, or 7×7 grids share a sheet. Two 8×8, 9×9, 10×10, 6×8, or 7×9 grids share a sheet. Large print is one grid on the sheet. The printable page isPipes packs.
- Hard5×5The one turn, the meeting turn, and the group that is too small. The closed side comes later on some of these grids.Play 5×5 →
- Hard9×9The one turn, the meeting turn, and the closed side. These grids do not say the group is too small.Play 9×9 →
There is no guide-sized seed to open. The boards above are teaching boards.