Pump

The Pump is used in conjunction with Pipes and Liquid Vents in order to transport Water (and other liquids except Lava). When a Pump that is touching a non-lava liquid is connected to a Liquid Vent via Pipes it will pick up that Water and it will be deposited out the other end from the Liquid Vent.

Pumps are non-solid to all pixels meaning that solid pixels (like Gold) can fall into them as well as Water. This will stop the liquids from also being able to occupy the space and therefore cause no liquid to be transported.

Like all blocks, the Pump takes up a 4 pixel x 4 pixel area. However, it is only the central 2 x 2 area that is actually able to pick up the liquid. This means that it only takes the bottom 3 of 4 layers of the Pump to be blocked by other pixels in order to completely stop functioning.

Given that only the bottom 4 pixels of the Pump are somewhat transparent, it can be hard to tell when there are pixels inside that are blocking it. The only easy way to tell is to hover you Grabber over the Pump to see if he highlights anything other than Water (or other liquid) in the tooltip. The different liquids are commingled so you must be careful to only connect one type of liquid into a network as all types of connected liquid will be output from all connected Liquid Vents. Mixing the liquids can work, but it needs a more complicated vent processing.