Function

• The plastic spray tower is often connected to two or more spray arms. The spray arms contain little holes that shoot hot water at dishes and other items in the dishwasher. The water collects in the tub at the bottom of the appliance. The spray tower's base typically rises a little, revealing the drain valve, where the dirty water exits.
  
  

Support and Impeller

• Beneath the tower's spray arms are two other cylinders, one white and one black. The white cylinder at the bottom is the wash arm support, and it connects the spray tower to a motor that rotates back and forth, spinning the spray arms. The spray tower and wash arm support are connected via the black cylinder, which is the impeller. The impeller pushes water upward through the spray tower and spray arms.
  
  

Variations

• Different dishwasher models use different types of spray towers. Some spray towers do not have spray arms; instead, they have holes along their sides that shoot water in all directions. The appearance of the spray tower varies among models, but its generic description of a white cylinder generally remains universal. A dishwasher may have a spray tower that comes through the bottom dish rack with spray arms below the rack, or it may not have a spray tower at all and has only spray arms connected to a wash arm support.
  
  

Replacement

• The spray tower is bound to degrade over time and with use. It also may become clogged, chipped or cracked, rendering it ineffective. Removing the spray tower to replace it is not a difficult task in most situations. Simply press down on the spray tower, and turn it counterclockwise to unlatch it from the tabs holding it in place over the impeller. It should lift out. If the spray tower is connected to spray arms, then its removal may require taking out the bottom dish rack.