Spawn a button trigger, set it to send an impulse to an impulse splitter on press. Then, spawn a curve data source, setting the curve to linear and "enabled" box unchecked. The start value should be zero, the end value determines how high the water rises, and the duration sets how fast it rises.
Next spawn an object position event, check "enabled" and go to "position Y" and press pick value object (Y) and select your curve data source. Then, go to select event targets and select your water. Next, spawn an interval trigger, with the interval as one tick, the start tick as zero, and "enabled" unchecked. Go to select event/filter and select the object position event. Then check disable after N impulses and make sure the max impulse sent count is equal to the duration (in ticks) of your curve data source.
Finally, spawn two state events, and connect the first to the interval trigger and the second to the curve data source. And then select the impulse splitter and connect that to the two state events. It should work now. But I may have been stupid and forgot something.
