Arranged in a star shape, the row of domino shaped tanks filled with water inputs at the bottom pivot so they can be knocked down and dump their water towards the center.
The smallest tanks on the outside are slightly tilted inwards so when they fill they fall inwards, hitting the next slightly larger
tank, which falls over in turn hitting the next tank till they all spill their water towards the middle creating a big splash as the water converges.
They're counter balanced so when empty they'll tilt back to upright to repeat the cycle.
See link for the effect.