Tap a pipe to turn it. Long-press, right-click or Shift+click turns it back.
Link the tap to the drain. Every open end the liquid reaches leaks — seal spare branches with a cap.
Zen levels: press Open tap when you are ready. A leak only pauses the water so you can fix it.
Flow levels: the liquid starts on its own when the timer runs out. Missions: it is already flowing. Keep turning pipes ahead of it — wet pipes are locked.
Tees split the stream, crosses carry two streams without mixing, bolted pipes and rocks never move. Tap a valve to open or close it, and a cracked pipe to patch it.
Arrows on one-way pipes, splitters and pumps show the only way the liquid may go. A filter cleans dirty water and acid for the clean tank.
Lava waits 3 s at an open end, then hardens. Gas rises: only a pump takes it down, and a gas leak spreads after 2 s.
Towers: drag or scroll the board to look up and down; the bar on the right shows the climb.
Stars: solve it within the move target for three stars. Undo, Reset and Hints are always free.
Keys: arrows move, Space turns, Backspace turns back, U undo, R reset, H hint, T open tap, P pause.